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[v2,00/12] Add functionality to ipu3-cio2 driver allowing software_node connections to sensors on platforms designed for Windows

Message ID 20201217234337.1983732-1-djrscally@gmail.com
Headers show
Series Add functionality to ipu3-cio2 driver allowing software_node connections to sensors on platforms designed for Windows | expand

Message

Daniel Scally Dec. 17, 2020, 11:43 p.m. UTC
Hello all

Previous version:
https://lore.kernel.org/linux-media/20201130133129.1024662-1-djrscally@gmail.com/T/#m91934e12e3d033da2e768e952ea3b4a125ee3e67
The RFC version before that:
https://lore.kernel.org/linux-media/20201019225903.14276-1-djrscally@gmail.com/

This series is to start adding support for webcams on laptops with ACPI tables
designed for use with CIO2 on Windows. This problem has two main parts; the
first part, which is handled in this series, is extending the ipu3-cio2
driver to allow for patching the firmware via software_nodes if endpoints
aren't defined by ACPI. The second is adding a new driver to handle power,
clocks and GPIO pins defined in DSDT tables in an awkward way. I decided to
split that second part out from this series, and instead give it its own
series (a v2 of which should land "soon"). The reasons for that are:

1. It's a logically separate change anyway
2. The recipients list was getting really long and
3. That probably meant that handling merge for all of this in one go was
   going to be impractically awkward.

Given how few comments the remaining patches of this series received in the
last posting, I'm hopeful that most or all of it could get picked up for 5.12.
We touch a few different areas:

lib (with an ack already)
  lib/test_printf.c: Use helper function to unwind array of
    software_nodes

drivers/base
  software_node: Fix refcounts in software_node_get_next_child()
  property: Return true in fwnode_device_is_available for NULL ops
  property: Call fwnode_graph_get_endpoint_by_id() for fwnode->secondary
  software_node: Enforce parent before child ordering of nodes arrays
  software_node: unregister software_nodes in reverse order

drivers/acpi
  acpi: Add acpi_dev_get_next_match_dev() and helper macro

drivers/media
  media: v4l2-core: v4l2-async: Check sd->fwnode->secondary in
    match_fwnode()
  ipu3-cio2: Add T: entry to MAINTAINERS
  ipu3-cio2: Rename ipu3-cio2.c
  ipu3-cio2: Add cio2-bridge to ipu3-cio2 driver

Given that, it feels sensible to me to try and merge them all through a single
tree; I was hoping the other maintainers would be amenable to having everything
merged through the media tree. Mauro; if that plan is ok (and of course assuming
that the rest of the patches are acked by their respective maintainers too),
could we get a dedicated feature branch just in case the following series ends
up being ready in time too? 

Series-level changelog:
	- Squashed the patches enforcing ordering in register/unregister_nodes()

More details of changes on each patch.

Comments as always very welcome - and thanks to everyone for all your help on
this so far, hope I've addressed everything from last time.

Dan

Daniel Scally (11):
  software_node: Fix refcounts in software_node_get_next_child()
  property: Return true in fwnode_device_is_available for NULL ops
  property: Call fwnode_graph_get_endpoint_by_id() for fwnode->secondary
  software_node: Enforce parent before child ordering of nodes arrays
  software_node: unregister software_nodes in reverse order
  lib/test_printf.c: Use helper function to unwind array of
    software_nodes
  ipu3-cio2: Add T: entry to MAINTAINERS
  ipu3-cio2: Rename ipu3-cio2.c
  media: v4l2-core: v4l2-async: Check sd->fwnode->secondary in
    match_fwnode()
  acpi: Add acpi_dev_get_next_match_dev() and helper macro
  ipu3-cio2: Add cio2-bridge to ipu3-cio2 driver

Heikki Krogerus (1):
  software_node: Add support for fwnode_graph*() family of functions

 MAINTAINERS                                   |   2 +
 drivers/acpi/utils.c                          |  30 +-
 drivers/base/property.c                       |  15 +-
 drivers/base/swnode.c                         | 173 +++++++++--
 drivers/media/pci/intel/ipu3/Kconfig          |  18 ++
 drivers/media/pci/intel/ipu3/Makefile         |   3 +
 drivers/media/pci/intel/ipu3/cio2-bridge.c    | 274 ++++++++++++++++++
 drivers/media/pci/intel/ipu3/cio2-bridge.h    | 122 ++++++++
 .../ipu3/{ipu3-cio2.c => ipu3-cio2-main.c}    |  34 +++
 drivers/media/pci/intel/ipu3/ipu3-cio2.h      |   6 +
 drivers/media/v4l2-core/v4l2-async.c          |   8 +
 include/acpi/acpi_bus.h                       |   7 +
 lib/test_printf.c                             |   4 +-
 13 files changed, 669 insertions(+), 27 deletions(-)
 create mode 100644 drivers/media/pci/intel/ipu3/cio2-bridge.c
 create mode 100644 drivers/media/pci/intel/ipu3/cio2-bridge.h
 rename drivers/media/pci/intel/ipu3/{ipu3-cio2.c => ipu3-cio2-main.c} (98%)

Comments

Laurent Pinchart Dec. 18, 2020, 4:22 p.m. UTC | #1
Hi Daniel,

Thank you for the patch.

On Thu, Dec 17, 2020 at 11:43:31PM +0000, Daniel Scally wrote:
> From: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> 
> This implements the remaining .graph_* callbacks in the
> fwnode operations structure for the software nodes. That makes
> the fwnode_graph*() functions available in the drivers also
> when software nodes are used.
> 
> The implementation tries to mimic the "OF graph" as much as
> possible, but there is no support for the "reg" device
> property. The ports will need to have the index in their
> name which starts with "port@" (for example "port@0", "port@1",
> ...) and endpoints will use the index of the software node
> that is given to them during creation. The port nodes can
> also be grouped under a specially named "ports" subnode,
> just like in DT, if necessary.
> 
> The remote-endpoints are reference properties under the
> endpoint nodes that are named "remote-endpoint".
> 
> Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> Co-developed-by: Daniel Scally <djrscally@gmail.com>
> Signed-off-by: Daniel Scally <djrscally@gmail.com>
> ---
> Changes in v2:
> 
> 	- Changed commit to specify port name prefix as port@
> 	- Accounted for that rename in *parse_endpoint()
> 
>  drivers/base/swnode.c | 110 +++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 109 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c
> index 2b90d380039b..0d14d5ebe441 100644
> --- a/drivers/base/swnode.c
> +++ b/drivers/base/swnode.c
> @@ -540,6 +540,110 @@ software_node_get_reference_args(const struct fwnode_handle *fwnode,
>  	return 0;
>  }
>  
> +static struct fwnode_handle *
> +swnode_graph_find_next_port(const struct fwnode_handle *parent,
> +			    struct fwnode_handle *port)
> +{
> +	struct fwnode_handle *old = port;
> +
> +	while ((port = software_node_get_next_child(parent, old))) {
> +		if (!strncmp(to_swnode(port)->node->name, "port", 4))

Maybe we'll need to limit this to matching on "port" or "port@[0-9]+" to
avoid false positives, but that can be done later, if needed.

> +			return port;
> +		old = port;
> +	}
> +
> +	return NULL;
> +}
> +
> +static struct fwnode_handle *
> +software_node_graph_get_next_endpoint(const struct fwnode_handle *fwnode,
> +				      struct fwnode_handle *endpoint)
> +{
> +	struct swnode *swnode = to_swnode(fwnode);
> +	struct fwnode_handle *old = endpoint;
> +	struct fwnode_handle *parent;
> +	struct fwnode_handle *port;
> +
> +	if (!swnode)
> +		return NULL;
> +
> +	if (endpoint) {
> +		port = software_node_get_parent(endpoint);

Here the reference count to port is incremented.

> +		parent = software_node_get_parent(port);
> +	} else {
> +		parent = software_node_get_named_child_node(fwnode, "ports");
> +		if (!parent)
> +			parent = software_node_get(&swnode->fwnode);
> +
> +		port = swnode_graph_find_next_port(parent, NULL);

But here it isn't, software_node_get_next_child() doesn't deal with
reference counts.

> +	}
> +
> +	for (; port; port = swnode_graph_find_next_port(parent, port)) {

So if the loop terminates normally, the reference acquired in the first
branch of the if will be leaked.

> +		endpoint = software_node_get_next_child(port, old);
> +		if (endpoint) {
> +			fwnode_handle_put(port);

While in this case the reference not acquired in the second branch of
the if will be released incorrectly.

I think it's software_node_get_next_child() that needs to be fixed if
I'm not mistaken.

> +			break;
> +		}
> +
> +		/* No more endpoints for that port, so stop passing old */
> +		old = NULL;

I wonder if you could drop the 'old' variable and use 'enpoint' in the
call to software_node_get_next_child(). You could then drop these two
lines.

> +	}
> +
> +	fwnode_handle_put(parent);
> +
> +	return endpoint;
> +}
> +
> +static struct fwnode_handle *
> +software_node_graph_get_remote_endpoint(const struct fwnode_handle *fwnode)
> +{
> +	struct swnode *swnode = to_swnode(fwnode);
> +	const struct software_node_ref_args *ref;
> +	const struct property_entry *prop;
> +
> +	if (!swnode)
> +		return NULL;
> +
> +	prop = property_entry_get(swnode->node->properties, "remote-endpoint");
> +	if (!prop || prop->type != DEV_PROP_REF || prop->is_inline)
> +		return NULL;
> +
> +	ref = prop->pointer;
> +
> +	return software_node_get(software_node_fwnode(ref[0].node));
> +}
> +
> +static struct fwnode_handle *
> +software_node_graph_get_port_parent(struct fwnode_handle *fwnode)
> +{
> +	struct swnode *swnode = to_swnode(fwnode);
> +	struct fwnode_handle *parent;
> +
> +	if (!strcmp(swnode->parent->node->name, "ports"))
> +		parent = &swnode->parent->parent->fwnode;
> +	else
> +		parent = &swnode->parent->fwnode;
> +
> +	return software_node_get(parent);
> +}
> +
> +static int
> +software_node_graph_parse_endpoint(const struct fwnode_handle *fwnode,
> +				   struct fwnode_endpoint *endpoint)
> +{
> +	struct swnode *swnode = to_swnode(fwnode);
> +	int ret;
> +
> +	ret = kstrtou32(swnode->parent->node->name + 5, 10, &endpoint->port);
> +	if (ret)
> +		return ret;
> +
> +	endpoint->id = swnode->id;
> +	endpoint->local_fwnode = fwnode;
> +
> +	return 0;
> +}
> +
>  static const struct fwnode_operations software_node_ops = {
>  	.get = software_node_get,
>  	.put = software_node_put,
> @@ -551,7 +655,11 @@ static const struct fwnode_operations software_node_ops = {
>  	.get_parent = software_node_get_parent,
>  	.get_next_child_node = software_node_get_next_child,
>  	.get_named_child_node = software_node_get_named_child_node,
> -	.get_reference_args = software_node_get_reference_args
> +	.get_reference_args = software_node_get_reference_args,
> +	.graph_get_next_endpoint = software_node_graph_get_next_endpoint,
> +	.graph_get_remote_endpoint = software_node_graph_get_remote_endpoint,
> +	.graph_get_port_parent = software_node_graph_get_port_parent,
> +	.graph_parse_endpoint = software_node_graph_parse_endpoint,
>  };
>  
>  /* -------------------------------------------------------------------------- */
Laurent Pinchart Dec. 18, 2020, 4:53 p.m. UTC | #2
Hi Daniel,

Thank you for the patch.

On Thu, Dec 17, 2020 at 11:43:37PM +0000, Daniel Scally wrote:
> Currently on platforms designed for Windows, connections between CIO2 and

> sensors are not properly defined in DSDT. This patch extends the ipu3-cio2

> driver to compensate by building software_node connections, parsing the

> connection properties from the sensor's SSDB buffer.

> 

> Suggested-by: Jordan Hand <jorhand@linux.microsoft.com>

> Signed-off-by: Daniel Scally <djrscally@gmail.com>

> ---

> Changes in v2:

> 

> 	- Dropped some headers

> 	- Added support for specifying link-frequencies in the array of

> 	cio2_supported_sensors and added that property to the endpoint.

> 	- Replaced strcpy with strscpy (Laurent, I liked your change better

> 	stylistically but ofc the string literals are lost when the module

> 	is reloaded)

> 	- Named the ports/endpoints "port@%u"

> 	- Added an overflow check to cio2_bridge_connect_sensors()

> 	- A bunch of cosmetic changes

> 

> For the cio2_supported_sensors array, specify link frequencies in this

> manner: 

> 

> 	CIO2_SENSOR_CONFIG("OVTI5648", 2, 16800000, 2100000)

> 

>  MAINTAINERS                                   |   1 +

>  drivers/media/pci/intel/ipu3/Kconfig          |  18 ++

>  drivers/media/pci/intel/ipu3/Makefile         |   1 +

>  drivers/media/pci/intel/ipu3/cio2-bridge.c    | 274 ++++++++++++++++++

>  drivers/media/pci/intel/ipu3/cio2-bridge.h    | 122 ++++++++

>  drivers/media/pci/intel/ipu3/ipu3-cio2-main.c |  34 +++

>  drivers/media/pci/intel/ipu3/ipu3-cio2.h      |   6 +

>  7 files changed, 456 insertions(+)

>  create mode 100644 drivers/media/pci/intel/ipu3/cio2-bridge.c

>  create mode 100644 drivers/media/pci/intel/ipu3/cio2-bridge.h

> 

> diff --git a/MAINTAINERS b/MAINTAINERS

> index 16b544624577..e7784b4bc8ea 100644

> --- a/MAINTAINERS

> +++ b/MAINTAINERS

> @@ -8943,6 +8943,7 @@ INTEL IPU3 CSI-2 CIO2 DRIVER

>  M:	Yong Zhi <yong.zhi@intel.com>

>  M:	Sakari Ailus <sakari.ailus@linux.intel.com>

>  M:	Bingbu Cao <bingbu.cao@intel.com>

> +M:	Dan Scally <djrscally@gmail.com>

>  R:	Tianshu Qiu <tian.shu.qiu@intel.com>

>  L:	linux-media@vger.kernel.org

>  S:	Maintained

> diff --git a/drivers/media/pci/intel/ipu3/Kconfig b/drivers/media/pci/intel/ipu3/Kconfig

> index 82d7f17e6a02..dcf5c4b74673 100644

> --- a/drivers/media/pci/intel/ipu3/Kconfig

> +++ b/drivers/media/pci/intel/ipu3/Kconfig

> @@ -16,3 +16,21 @@ config VIDEO_IPU3_CIO2

>  	  Say Y or M here if you have a Skylake/Kaby Lake SoC with MIPI CSI-2

>  	  connected camera.

>  	  The module will be called ipu3-cio2.

> +

> +config CIO2_BRIDGE

> +	bool "IPU3 CIO2 Sensors Bridge"

> +	depends on VIDEO_IPU3_CIO2

> +	help

> +	  This extension provides an API for the ipu3-cio2 driver to create

> +	  connections to cameras that are hidden in SSDB buffer in ACPI. It

> +	  can be used to enable support for cameras in detachable / hybrid

> +	  devices that ship with Windows.

> +

> +	  Say Y here if your device is a detachable / hybrid laptop that comes

> +	  with Windows installed by the OEM, for example:

> +

> +		- Microsoft Surface models (except Surface Pro 3)

> +		- The Lenovo Miix line (for example the 510, 520, 710 and 720)

> +		- Dell 7285

> +

> +	  If in doubt, say N here.

> diff --git a/drivers/media/pci/intel/ipu3/Makefile b/drivers/media/pci/intel/ipu3/Makefile

> index 429d516452e4..933777e6ea8a 100644

> --- a/drivers/media/pci/intel/ipu3/Makefile

> +++ b/drivers/media/pci/intel/ipu3/Makefile

> @@ -2,3 +2,4 @@

>  obj-$(CONFIG_VIDEO_IPU3_CIO2) += ipu3-cio2.o

>  

>  ipu3-cio2-y += ipu3-cio2-main.o

> +ipu3-cio2-$(CONFIG_CIO2_BRIDGE) += cio2-bridge.o

> diff --git a/drivers/media/pci/intel/ipu3/cio2-bridge.c b/drivers/media/pci/intel/ipu3/cio2-bridge.c

> new file mode 100644

> index 000000000000..3f0e2d7eab20

> --- /dev/null

> +++ b/drivers/media/pci/intel/ipu3/cio2-bridge.c

> @@ -0,0 +1,274 @@

> +// SPDX-License-Identifier: GPL-2.0

> +/* Author: Dan Scally <djrscally@gmail.com> */

> +

> +#include <linux/acpi.h>

> +#include <linux/device.h>

> +#include <linux/pci.h>

> +#include <linux/property.h>

> +

> +#include "cio2-bridge.h"

> +

> +/*

> + * Extend this array with ACPI Hardware ID's of devices known to be working

> + * plus the number of link-frequencies expected by their drivers, along with

> + * the frequency values in hertz. This is somewhat opportunistic way of adding

> + * support for this for now in the hopes of a better source for the information

> + * (possibly some encoded value in the SSDB buffer that we're unaware of)

> + * becoming apparent in the future.

> + *

> + * Do not add an entry for a sensor that is not actually supported.

> + */

> +static const struct cio2_sensor_config cio2_supported_sensors[] = {

> +	CIO2_SENSOR_CONFIG("INT33BE", 0),

> +	CIO2_SENSOR_CONFIG("OVTI2680", 0),

> +};

> +

> +static int cio2_bridge_read_acpi_buffer(struct acpi_device *adev, char *id,

> +					void *data, u32 size)

> +{

> +	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };

> +	union acpi_object *obj;

> +	acpi_status status;

> +	int ret;

> +

> +	status = acpi_evaluate_object(adev->handle, id, NULL, &buffer);

> +	if (ACPI_FAILURE(status))

> +		return -ENODEV;

> +

> +	obj = buffer.pointer;

> +	if (!obj) {

> +		dev_err(&adev->dev, "Couldn't locate ACPI buffer\n");

> +		return -ENODEV;

> +	}

> +

> +	if (obj->type != ACPI_TYPE_BUFFER) {

> +		dev_err(&adev->dev, "Not an ACPI buffer\n");

> +		ret = -ENODEV;

> +		goto out_free_buff;

> +	}

> +

> +	if (obj->buffer.length > size) {

> +		dev_err(&adev->dev, "Given buffer is too small\n");

> +		ret = -EINVAL;

> +		goto out_free_buff;

> +	}

> +

> +	memcpy(data, obj->buffer.pointer, obj->buffer.length);

> +	ret = obj->buffer.length;

> +

> +out_free_buff:

> +	kfree(buffer.pointer);

> +	return ret;

> +}

> +

> +static void cio2_bridge_init_property_names(struct cio2_sensor *sensor)

> +{

> +	strscpy(sensor->prop_names.clock_frequency, "clock-frequency",

> +		sizeof(sensor->prop_names.clock_frequency));

> +	strscpy(sensor->prop_names.rotation, "rotation",

> +		sizeof(sensor->prop_names.rotation));

> +	strscpy(sensor->prop_names.bus_type, "bus-type",

> +		sizeof(sensor->prop_names.bus_type));

> +	strscpy(sensor->prop_names.data_lanes, "data-lanes",

> +		sizeof(sensor->prop_names.data_lanes));

> +	strscpy(sensor->prop_names.remote_endpoint, "remote-endpoint",

> +		sizeof(sensor->prop_names.remote_endpoint));

> +	strscpy(sensor->prop_names.link_frequencies, "link-frequencies",

> +		sizeof(sensor->prop_names.link_frequencies));


Just curious, was there anything not working correctly with the proposal
I made ?

static const struct cio2_property_names prop_names = {
	.clock_frequency = "clock-frequency",
	.rotation = "rotation",
	.bus_type = "bus-type",
	.data_lanes = "data-lanes",
	.remote_endpoint = "remote-endpoint",
};

static void cio2_bridge_init_property_names(struct cio2_sensor *sensor)
{
	sensor->prop_names = prop_names;
}

It generates a warning when the string is too long for the field size,
which should help catching issues at compilation time.

> +}

> +

> +static void cio2_bridge_create_fwnode_properties(struct cio2_sensor *sensor,

> +						 const struct cio2_sensor_config *cfg)

> +{

> +	unsigned int i;

> +

> +	cio2_bridge_init_property_names(sensor);

> +

> +	for (i = 0; i < 4; i++)

> +		sensor->data_lanes[i] = i + 1;

> +

> +	sensor->local_ref[0].node = &sensor->swnodes[SWNODE_CIO2_ENDPOINT];

> +	sensor->remote_ref[0].node = &sensor->swnodes[SWNODE_SENSOR_ENDPOINT];

> +

> +	sensor->dev_properties[0] = PROPERTY_ENTRY_U32(sensor->prop_names.clock_frequency,

> +						       sensor->ssdb.mclkspeed);

> +	sensor->dev_properties[1] = PROPERTY_ENTRY_U8(sensor->prop_names.rotation,

> +						      sensor->ssdb.degree);

> +

> +	sensor->ep_properties[0] = PROPERTY_ENTRY_U32(sensor->prop_names.bus_type, 4);

> +	sensor->ep_properties[1] = PROPERTY_ENTRY_U32_ARRAY_LEN(sensor->prop_names.data_lanes,

> +								sensor->data_lanes,

> +								sensor->ssdb.lanes);

> +	sensor->ep_properties[2] = PROPERTY_ENTRY_REF_ARRAY(sensor->prop_names.remote_endpoint,

> +							    sensor->local_ref);

> +

> +	if (cfg->nr_link_freqs > 0)

> +		sensor->ep_properties[3] = PROPERTY_ENTRY_U64_ARRAY_LEN(

> +						sensor->prop_names.link_frequencies,

> +						cfg->link_freqs,

> +						cfg->nr_link_freqs);

> +

> +	sensor->cio2_properties[0] = PROPERTY_ENTRY_U32_ARRAY_LEN(sensor->prop_names.data_lanes,

> +								  sensor->data_lanes,

> +								  sensor->ssdb.lanes);

> +	sensor->cio2_properties[1] = PROPERTY_ENTRY_REF_ARRAY(sensor->prop_names.remote_endpoint,

> +							      sensor->remote_ref);

> +}

> +

> +static void cio2_bridge_init_swnode_names(struct cio2_sensor *sensor)

> +{

> +	snprintf(sensor->node_names.remote_port, 7, "port@%u", sensor->ssdb.link);

> +	strscpy(sensor->node_names.port, "port@0", sizeof(sensor->node_names.port));

> +	strscpy(sensor->node_names.endpoint, "endpoint@0", sizeof(sensor->node_names.endpoint));


I'd wrap lines, but maybe that's because I'm an old-school, 80-columns
programmer :-)

> +}

> +

> +static void cio2_bridge_create_connection_swnodes(struct cio2_bridge *bridge,

> +						  struct cio2_sensor *sensor)

> +{

> +	struct software_node *nodes = sensor->swnodes;

> +

> +	cio2_bridge_init_swnode_names(sensor);

> +

> +	nodes[SWNODE_SENSOR_HID] = NODE_SENSOR(sensor->name,

> +					       sensor->dev_properties);

> +	nodes[SWNODE_SENSOR_PORT] = NODE_PORT(sensor->node_names.port,

> +					      &nodes[SWNODE_SENSOR_HID]);

> +	nodes[SWNODE_SENSOR_ENDPOINT] = NODE_ENDPOINT(sensor->node_names.endpoint,

> +						      &nodes[SWNODE_SENSOR_PORT],

> +						      sensor->ep_properties);

> +	nodes[SWNODE_CIO2_PORT] = NODE_PORT(sensor->node_names.remote_port,

> +					    &bridge->cio2_hid_node);

> +	nodes[SWNODE_CIO2_ENDPOINT] = NODE_ENDPOINT(sensor->node_names.endpoint,

> +						    &nodes[SWNODE_CIO2_PORT],

> +						    sensor->cio2_properties);

> +}

> +

> +static void cio2_bridge_unregister_sensors(struct cio2_bridge *bridge)

> +{

> +	struct cio2_sensor *sensor;

> +	unsigned int i;

> +

> +	for (i = 0; i < bridge->n_sensors; i++) {

> +		sensor = &bridge->sensors[i];

> +		software_node_unregister_nodes(sensor->swnodes);

> +		acpi_dev_put(sensor->adev);

> +	}

> +}

> +

> +static int cio2_bridge_connect_sensors(struct cio2_bridge *bridge,

> +				       struct pci_dev *cio2)

> +{

> +	struct fwnode_handle *fwnode;

> +	struct cio2_sensor *sensor;

> +	struct acpi_device *adev;

> +	unsigned int i;

> +	int ret = 0;

> +

> +	for (i = 0; i < ARRAY_SIZE(cio2_supported_sensors); i++) {

> +		const struct cio2_sensor_config *cfg = &cio2_supported_sensors[i];

> +

> +		for_each_acpi_dev_match(adev, cfg->hid, NULL, -1) {

> +			if (bridge->n_sensors >= CIO2_NUM_PORTS) {

> +				dev_warn(&cio2->dev, "Exceeded available CIO2 ports\n");

> +				/* overflow i so outer loop ceases */

> +				i = ARRAY_SIZE(cio2_supported_sensors);

> +				break;


Or just

				return 0;

?

> +			}

> +

> +			if (!adev->status.enabled)

> +				continue;

> +

> +			sensor = &bridge->sensors[bridge->n_sensors];

> +			sensor->adev = adev;

> +			strscpy(sensor->name, cfg->hid, sizeof(sensor->name));

> +

> +			ret = cio2_bridge_read_acpi_buffer(adev, "SSDB",

> +							   &sensor->ssdb,

> +							   sizeof(sensor->ssdb));

> +			if (ret < 0)

> +				goto err_put_adev;

> +

> +			if (sensor->ssdb.lanes > 4) {

> +				dev_err(&adev->dev,

> +					"Number of lanes in SSDB is invalid\n");

> +				goto err_put_adev;

> +			}

> +

> +			cio2_bridge_create_fwnode_properties(sensor, cfg);

> +			cio2_bridge_create_connection_swnodes(bridge, sensor);

> +

> +			ret = software_node_register_nodes(sensor->swnodes);

> +			if (ret)

> +				goto err_put_adev;

> +

> +			fwnode = software_node_fwnode(&sensor->swnodes[SWNODE_SENSOR_HID]);

> +			if (!fwnode) {

> +				ret = -ENODEV;

> +				goto err_free_swnodes;

> +			}

> +

> +			adev->fwnode.secondary = fwnode;

> +

> +			dev_info(&cio2->dev, "Found supported sensor %s\n",

> +				 acpi_dev_name(adev));

> +

> +			bridge->n_sensors++;

> +		}

> +	}

> +

> +	return ret;

> +

> +err_free_swnodes:

> +	software_node_unregister_nodes(sensor->swnodes);

> +err_put_adev:

> +	acpi_dev_put(sensor->adev);

> +

> +	return ret;

> +}

> +

> +int cio2_bridge_init(struct pci_dev *cio2)

> +{

> +	struct device *dev = &cio2->dev;

> +	struct fwnode_handle *fwnode;

> +	struct cio2_bridge *bridge;

> +	int ret;

> +

> +	bridge = kzalloc(sizeof(*bridge), GFP_KERNEL);

> +	if (!bridge)

> +		return -ENOMEM;

> +

> +	strscpy(bridge->cio2_node_name, CIO2_HID, sizeof(bridge->cio2_node_name));

> +	bridge->cio2_hid_node.name = bridge->cio2_node_name;

> +

> +	ret = software_node_register(&bridge->cio2_hid_node);

> +	if (ret < 0) {

> +		dev_err(dev, "Failed to register the CIO2 HID node\n");

> +		goto err_free_bridge;

> +	}

> +

> +	ret = cio2_bridge_connect_sensors(bridge, cio2);

> +	if (ret || bridge->n_sensors == 0)

> +		goto err_unregister_cio2;

> +

> +	dev_info(dev, "Connected %d cameras\n", bridge->n_sensors);

> +

> +	fwnode = software_node_fwnode(&bridge->cio2_hid_node);

> +	if (!fwnode) {

> +		dev_err(dev, "Error getting fwnode from cio2 software_node\n");

> +		ret = -ENODEV;

> +		goto err_unregister_sensors;

> +	}

> +

> +	set_secondary_fwnode(dev, fwnode);

> +

> +	return 0;

> +

> +err_unregister_sensors:

> +	cio2_bridge_unregister_sensors(bridge);

> +err_unregister_cio2:

> +	software_node_unregister(&bridge->cio2_hid_node);

> +err_free_bridge:

> +	kfree(bridge);

> +

> +	return ret;

> +}

> diff --git a/drivers/media/pci/intel/ipu3/cio2-bridge.h b/drivers/media/pci/intel/ipu3/cio2-bridge.h

> new file mode 100644

> index 000000000000..f89a8e33f82c

> --- /dev/null

> +++ b/drivers/media/pci/intel/ipu3/cio2-bridge.h

> @@ -0,0 +1,122 @@

> +/* SPDX-License-Identifier: GPL-2.0 */

> +/* Author: Dan Scally <djrscally@gmail.com> */

> +#ifndef __CIO2_BRIDGE_H

> +#define __CIO2_BRIDGE_H

> +

> +#include <linux/property.h>

> +

> +#define CIO2_HID				"INT343E"

> +#define CIO2_NUM_PORTS				4

> +#define MAX_NUM_LINK_FREQS			3

> +

> +#define CIO2_SENSOR_CONFIG(_HID, _NR, ...)	\

> +	{					\

> +		.hid = _HID,			\

> +		.nr_link_freqs = _NR,		\

> +		.link_freqs = { __VA_ARGS__ }	\

> +	}

> +

> +#define NODE_SENSOR(_HID, _PROPS)		\

> +	((const struct software_node) {		\

> +		.name = _HID,			\

> +		.properties = _PROPS,		\

> +	})

> +

> +#define NODE_PORT(_PORT, _SENSOR_NODE)		\

> +	((const struct software_node) {		\

> +		_PORT,				\

> +		_SENSOR_NODE,			\

> +	})

> +

> +#define NODE_ENDPOINT(_EP, _PORT, _PROPS)	\

> +	((const struct software_node) {		\

> +		_EP,				\

> +		_PORT,				\

> +		_PROPS,				\

> +	})

> +

> +enum cio2_sensor_swnodes {

> +	SWNODE_SENSOR_HID,

> +	SWNODE_SENSOR_PORT,

> +	SWNODE_SENSOR_ENDPOINT,

> +	SWNODE_CIO2_PORT,

> +	SWNODE_CIO2_ENDPOINT,

> +	NR_OF_SENSOR_SWNODES

> +};

> +

> +/* Data representation as it is in ACPI SSDB buffer */

> +struct cio2_sensor_ssdb {

> +	u8 version;				/* 0000 */

> +	u8 sku;					/* 0001 */

> +	u8 guid_csi2[16];			/* 0002 */

> +	u8 devfunction;				/* 0003 */

> +	u8 bus;					/* 0004 */

> +	u32 dphylinkenfuses;			/* 0005 */

> +	u32 clockdiv;				/* 0009 */

> +	u8 link;				/* 0013 */

> +	u8 lanes;				/* 0014 */

> +	u32 csiparams[10];			/* 0015 */

> +	u32 maxlanespeed;			/* 0019 */

> +	u8 sensorcalibfileidx;			/* 0023 */

> +	u8 sensorcalibfileidxInMBZ[3];		/* 0024 */

> +	u8 romtype;				/* 0025 */

> +	u8 vcmtype;				/* 0026 */

> +	u8 platforminfo;			/* 0027 */


Why stop at 27 ? :-) I'd either go all the way, or not at all. It's also
quite customary to represent offset as hex values, as that's what most
hex editors / viewers will show.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>


> +	u8 platformsubinfo;

> +	u8 flash;

> +	u8 privacyled;

> +	u8 degree;

> +	u8 mipilinkdefined;

> +	u32 mclkspeed;

> +	u8 controllogicid;

> +	u8 reserved1[3];

> +	u8 mclkport;

> +	u8 reserved2[13];

> +} __packed;

> +

> +struct cio2_property_names {

> +	char clock_frequency[16];

> +	char rotation[9];

> +	char bus_type[9];

> +	char data_lanes[11];

> +	char remote_endpoint[16];

> +	char link_frequencies[17];

> +};

> +

> +struct cio2_node_names {

> +	char port[7];

> +	char endpoint[11];

> +	char remote_port[7];

> +};

> +

> +struct cio2_sensor_config {

> +	const char *hid;

> +	const u8 nr_link_freqs;

> +	const u64 link_freqs[MAX_NUM_LINK_FREQS];

> +};

> +

> +struct cio2_sensor {

> +	char name[ACPI_ID_LEN];

> +	struct acpi_device *adev;

> +

> +	struct software_node swnodes[6];

> +	struct cio2_node_names node_names;

> +

> +	u32 data_lanes[4];

> +	struct cio2_sensor_ssdb ssdb;

> +	struct cio2_property_names prop_names;

> +	struct property_entry ep_properties[5];

> +	struct property_entry dev_properties[3];

> +	struct property_entry cio2_properties[3];

> +	struct software_node_ref_args local_ref[1];

> +	struct software_node_ref_args remote_ref[1];

> +};

> +

> +struct cio2_bridge {

> +	char cio2_node_name[ACPI_ID_LEN];

> +	struct software_node cio2_hid_node;

> +	unsigned int n_sensors;

> +	struct cio2_sensor sensors[CIO2_NUM_PORTS];

> +};

> +

> +#endif

> diff --git a/drivers/media/pci/intel/ipu3/ipu3-cio2-main.c b/drivers/media/pci/intel/ipu3/ipu3-cio2-main.c

> index 36e354ecf71e..68ff28abc6a3 100644

> --- a/drivers/media/pci/intel/ipu3/ipu3-cio2-main.c

> +++ b/drivers/media/pci/intel/ipu3/ipu3-cio2-main.c

> @@ -1702,11 +1702,28 @@ static void cio2_queues_exit(struct cio2_device *cio2)

>  		cio2_queue_exit(cio2, &cio2->queue[i]);

>  }

>  

> +static bool cio2_check_fwnode_graph(struct fwnode_handle *fwnode)

> +{

> +	struct fwnode_handle *endpoint;

> +

> +	if (IS_ERR_OR_NULL(fwnode))

> +		return false;

> +

> +	endpoint = fwnode_graph_get_next_endpoint(fwnode, NULL);

> +	if (endpoint) {

> +		fwnode_handle_put(endpoint);

> +		return true;

> +	}

> +

> +	return cio2_check_fwnode_graph(fwnode->secondary);

> +}

> +

>  /**************** PCI interface ****************/

>  

>  static int cio2_pci_probe(struct pci_dev *pci_dev,

>  			  const struct pci_device_id *id)

>  {

> +	struct fwnode_handle *fwnode = dev_fwnode(&pci_dev->dev);

>  	struct cio2_device *cio2;

>  	int r;

>  

> @@ -1715,6 +1732,23 @@ static int cio2_pci_probe(struct pci_dev *pci_dev,

>  		return -ENOMEM;

>  	cio2->pci_dev = pci_dev;

>  

> +	/*

> +	 * On some platforms no connections to sensors are defined in firmware,

> +	 * if the device has no endpoints then we can try to build those as

> +	 * software_nodes parsed from SSDB.

> +	 */

> +	if (!cio2_check_fwnode_graph(fwnode)) {

> +		if (fwnode && !IS_ERR_OR_NULL(fwnode->secondary)) {

> +			dev_err(&pci_dev->dev,

> +				"fwnode graph has no endpoints connected\n");

> +			return -EINVAL;

> +		}

> +

> +		r = cio2_bridge_init(pci_dev);

> +		if (r)

> +			return r;

> +	}

> +

>  	r = pcim_enable_device(pci_dev);

>  	if (r) {

>  		dev_err(&pci_dev->dev, "failed to enable device (%d)\n", r);

> diff --git a/drivers/media/pci/intel/ipu3/ipu3-cio2.h b/drivers/media/pci/intel/ipu3/ipu3-cio2.h

> index ccf0b85ae36f..520a27c9cdad 100644

> --- a/drivers/media/pci/intel/ipu3/ipu3-cio2.h

> +++ b/drivers/media/pci/intel/ipu3/ipu3-cio2.h

> @@ -437,4 +437,10 @@ static inline struct cio2_queue *vb2q_to_cio2_queue(struct vb2_queue *vq)

>  	return container_of(vq, struct cio2_queue, vbq);

>  }

>  

> +#if IS_ENABLED(CONFIG_CIO2_BRIDGE)

> +int cio2_bridge_init(struct pci_dev *cio2);

> +#else

> +int cio2_bridge_init(struct pci_dev *cio2) { return 0; }

> +#endif

> +

>  #endif


-- 
Regards,

Laurent Pinchart
Andy Shevchenko Dec. 18, 2020, 8:37 p.m. UTC | #3
On Thu, Dec 17, 2020 at 11:43:31PM +0000, Daniel Scally wrote:
> From: Heikki Krogerus <heikki.krogerus@linux.intel.com>

> 

> This implements the remaining .graph_* callbacks in the

> fwnode operations structure for the software nodes. That makes

> the fwnode_graph*() functions available in the drivers also

> when software nodes are used.

> 

> The implementation tries to mimic the "OF graph" as much as

> possible, but there is no support for the "reg" device

> property. The ports will need to have the index in their

> name which starts with "port@" (for example "port@0", "port@1",

> ...) and endpoints will use the index of the software node

> that is given to them during creation. The port nodes can

> also be grouped under a specially named "ports" subnode,

> just like in DT, if necessary.

> 

> The remote-endpoints are reference properties under the

> endpoint nodes that are named "remote-endpoint".


...

> +	while ((port = software_node_get_next_child(parent, old))) {

> +		if (!strncmp(to_swnode(port)->node->name, "port", 4))

> +			return port;

> +		old = port;

> +	}


Dunno if we need defines for port and its length here.

...

> +	ret = kstrtou32(swnode->parent->node->name + 5, 10, &endpoint->port);


But here at least comment is needed what 5 means ('port@' I suppose).

> +	if (ret)

> +		return ret;



-- 
With Best Regards,
Andy Shevchenko
Andy Shevchenko Dec. 18, 2020, 8:42 p.m. UTC | #4
On Thu, Dec 17, 2020 at 11:43:36PM +0000, Daniel Scally wrote:
> To ensure we handle situations in which multiple sensors of the same
> model (and therefore _HID) are present in a system, we need to be able
> to iterate over devices matching a known _HID but unknown _UID and _HRV
>  - add acpi_dev_get_next_match_dev() to accommodate that possibility and
> change acpi_dev_get_first_match_dev() to simply call the new function
> with a NULL starting point. Add an iterator macro for convenience.

...

> - * acpi_dev_get_first_match_dev - Return the first match of ACPI device
> + * acpi_dev_get_next_match_dev - Return the next match of ACPI device
> + * @adev: Pointer to the previous acpi_device matching this hid, uid and hrv

A nit: @hid, @uid and @hrv

>   * @hid: Hardware ID of the device.
>   * @uid: Unique ID of the device, pass NULL to not check _UID
>   * @hrv: Hardware Revision of the device, pass -1 to not check _HRV
Andy Shevchenko Dec. 18, 2020, 9:17 p.m. UTC | #5
On Thu, Dec 17, 2020 at 11:43:37PM +0000, Daniel Scally wrote:
> Currently on platforms designed for Windows, connections between CIO2 and

> sensors are not properly defined in DSDT. This patch extends the ipu3-cio2

> driver to compensate by building software_node connections, parsing the

> connection properties from the sensor's SSDB buffer.


...

> +	sensor->ep_properties[0] = PROPERTY_ENTRY_U32(sensor->prop_names.bus_type, 4);


Does 4 has any meaning that can be described by #define ?

...

> +static void cio2_bridge_init_swnode_names(struct cio2_sensor *sensor)

> +{

> +	snprintf(sensor->node_names.remote_port, 7, "port@%u", sensor->ssdb.link);


Hmm... I think you should use actual size of remote_port instead of 7.

> +	strscpy(sensor->node_names.port, "port@0", sizeof(sensor->node_names.port));


Yeah, I would rather like to see one point of the definition of the format.
If it's the same as per OF case, perhaps some generic header (like fwnode.h?) is good for this?
In this case the 5 in one of the previous patches Also can be derived from the format.

> +	strscpy(sensor->node_names.endpoint, "endpoint@0", sizeof(sensor->node_names.endpoint));


Similar here.

> +}


...

> +	for (i = 0; i < ARRAY_SIZE(cio2_supported_sensors); i++) {

> +		const struct cio2_sensor_config *cfg = &cio2_supported_sensors[i];

> +

> +		for_each_acpi_dev_match(adev, cfg->hid, NULL, -1) {


> +			if (bridge->n_sensors >= CIO2_NUM_PORTS) {

> +				dev_warn(&cio2->dev, "Exceeded available CIO2 ports\n");


> +				/* overflow i so outer loop ceases */

> +				i = ARRAY_SIZE(cio2_supported_sensors);

> +				break;


Why not to create a new label below and assign ret here with probably comment
why it's not an error?

> +			}


...

> +			ret = cio2_bridge_read_acpi_buffer(adev, "SSDB",

> +							   &sensor->ssdb,

> +							   sizeof(sensor->ssdb));

> +			if (ret < 0)


if (ret) (because positive case can be returned just by next conditional).

> +				goto err_put_adev;

> +

> +			if (sensor->ssdb.lanes > 4) {

> +				dev_err(&adev->dev,

> +					"Number of lanes in SSDB is invalid\n");

> +				goto err_put_adev;

> +			}


...

> +			dev_info(&cio2->dev, "Found supported sensor %s\n",

> +				 acpi_dev_name(adev));

> +

> +			bridge->n_sensors++;

> +		}

> +	}


	return 0;

> +err_free_swnodes:

> +	software_node_unregister_nodes(sensor->swnodes);

> +err_put_adev:

> +	acpi_dev_put(sensor->adev);


err_out:

> +	return ret;

> +}


...

> +enum cio2_sensor_swnodes {

> +	SWNODE_SENSOR_HID,

> +	SWNODE_SENSOR_PORT,

> +	SWNODE_SENSOR_ENDPOINT,

> +	SWNODE_CIO2_PORT,

> +	SWNODE_CIO2_ENDPOINT,


> +	NR_OF_SENSOR_SWNODES


Perhaps same namespace, i.e.

	SWNODE_SENSOR_NR

> +};


-- 
With Best Regards,
Andy Shevchenko
Daniel Scally Dec. 18, 2020, 10:13 p.m. UTC | #6
Hi Laurent - thanks for comments as always

On 18/12/2020 16:22, Laurent Pinchart wrote:
> Hi Daniel,
> 
> Thank you for the patch.
> 
> On Thu, Dec 17, 2020 at 11:43:31PM +0000, Daniel Scally wrote:
>> From: Heikki Krogerus <heikki.krogerus@linux.intel.com>
>>
>> This implements the remaining .graph_* callbacks in the
>> fwnode operations structure for the software nodes. That makes
>> the fwnode_graph*() functions available in the drivers also
>> when software nodes are used.
>>
>> The implementation tries to mimic the "OF graph" as much as
>> possible, but there is no support for the "reg" device
>> property. The ports will need to have the index in their
>> name which starts with "port@" (for example "port@0", "port@1",
>> ...) and endpoints will use the index of the software node
>> that is given to them during creation. The port nodes can
>> also be grouped under a specially named "ports" subnode,
>> just like in DT, if necessary.
>>
>> The remote-endpoints are reference properties under the
>> endpoint nodes that are named "remote-endpoint".
>>
>> Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
>> Co-developed-by: Daniel Scally <djrscally@gmail.com>
>> Signed-off-by: Daniel Scally <djrscally@gmail.com>
>> ---
>> Changes in v2:
>>
>> 	- Changed commit to specify port name prefix as port@
>> 	- Accounted for that rename in *parse_endpoint()
>>
>>  drivers/base/swnode.c | 110 +++++++++++++++++++++++++++++++++++++++++-
>>  1 file changed, 109 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c
>> index 2b90d380039b..0d14d5ebe441 100644
>> --- a/drivers/base/swnode.c
>> +++ b/drivers/base/swnode.c
>> @@ -540,6 +540,110 @@ software_node_get_reference_args(const struct fwnode_handle *fwnode,
>>  	return 0;
>>  }
>>  
>> +static struct fwnode_handle *
>> +swnode_graph_find_next_port(const struct fwnode_handle *parent,
>> +			    struct fwnode_handle *port)
>> +{
>> +	struct fwnode_handle *old = port;
>> +
>> +	while ((port = software_node_get_next_child(parent, old))) {
>> +		if (!strncmp(to_swnode(port)->node->name, "port", 4))
> 
> Maybe we'll need to limit this to matching on "port" or "port@[0-9]+" to
> avoid false positives, but that can be done later, if needed.

Hmm yeah I guess that's a danger - ok, I'll stick it on the list.


>> +			return port;
>> +		old = port;
>> +	}
>> +
>> +	return NULL;
>> +}
>> +
>> +static struct fwnode_handle *
>> +software_node_graph_get_next_endpoint(const struct fwnode_handle *fwnode,
>> +				      struct fwnode_handle *endpoint)
>> +{
>> +	struct swnode *swnode = to_swnode(fwnode);
>> +	struct fwnode_handle *old = endpoint;
>> +	struct fwnode_handle *parent;
>> +	struct fwnode_handle *port;
>> +
>> +	if (!swnode)
>> +		return NULL;
>> +
>> +	if (endpoint) {
>> +		port = software_node_get_parent(endpoint);
> 
> Here the reference count to port is incremented.
> 
>> +		parent = software_node_get_parent(port);
>> +	} else {
>> +		parent = software_node_get_named_child_node(fwnode, "ports");
>> +		if (!parent)
>> +			parent = software_node_get(&swnode->fwnode);
>> +
>> +		port = swnode_graph_find_next_port(parent, NULL);
> 
> But here it isn't, software_node_get_next_child() doesn't deal with
> reference counts.

Not as in the kernel right now, but after patch one of this series, it does:

[PATCH v2 01/12] software_node: Fix refcounts in
software_node_get_next_child()

I'm not sure that one linked to the thread correctly, but it's here if
you haven't seen it:

https://lore.kernel.org/linux-media/20201217234337.1983732-2-djrscally@gmail.com/T/#u

The tl;dr of the change is that it will now get() the next node (if
found) and **always** put() if one is passed.


>> +	}
>> +
>> +	for (; port; port = swnode_graph_find_next_port(parent, port)) {
> 
> So if the loop terminates normally, the reference acquired in the first
> branch of the if will be leaked.
> 
>> +		endpoint = software_node_get_next_child(port, old);
>> +		if (endpoint) {
>> +			fwnode_handle_put(port);
> 
> While in this case the reference not acquired in the second branch of
> the if will be released incorrectly.
> 
> I think it's software_node_get_next_child() that needs to be fixed if
> I'm not mistaken.

I think that's all handled in software_node_get_next_child() as amended
by 01/12. The net effect of get_next_endpoint() should be one refcount
increased for any endpoint returned, and 0 change to parent and any ports.


>> +			break;
>> +		}
>> +
>> +		/* No more endpoints for that port, so stop passing old */
>> +		old = NULL;
> 
> I wonder if you could drop the 'old' variable and use 'enpoint' in the
> call to software_node_get_next_child(). You could then drop these two
> lines.

That won't work, because endpoint would at that point not be a child of
the port we're passing, and the function relies on it being one:

	if (!p || list_empty(&p->children) ||
	    (c && list_is_last(&c->entry, &p->children))) {
		fwnode_handle_put(child);
		return NULL;
	}

>> +	}
>> +
>> +	fwnode_handle_put(parent);
>> +
>> +	return endpoint;
>> +}
>> +
>> +static struct fwnode_handle *
>> +software_node_graph_get_remote_endpoint(const struct fwnode_handle *fwnode)
>> +{
>> +	struct swnode *swnode = to_swnode(fwnode);
>> +	const struct software_node_ref_args *ref;
>> +	const struct property_entry *prop;
>> +
>> +	if (!swnode)
>> +		return NULL;
>> +
>> +	prop = property_entry_get(swnode->node->properties, "remote-endpoint");
>> +	if (!prop || prop->type != DEV_PROP_REF || prop->is_inline)
>> +		return NULL;
>> +
>> +	ref = prop->pointer;
>> +
>> +	return software_node_get(software_node_fwnode(ref[0].node));
>> +}
>> +
>> +static struct fwnode_handle *
>> +software_node_graph_get_port_parent(struct fwnode_handle *fwnode)
>> +{
>> +	struct swnode *swnode = to_swnode(fwnode);
>> +	struct fwnode_handle *parent;
>> +
>> +	if (!strcmp(swnode->parent->node->name, "ports"))
>> +		parent = &swnode->parent->parent->fwnode;
>> +	else
>> +		parent = &swnode->parent->fwnode;
>> +
>> +	return software_node_get(parent);
>> +}
>> +
>> +static int
>> +software_node_graph_parse_endpoint(const struct fwnode_handle *fwnode,
>> +				   struct fwnode_endpoint *endpoint)
>> +{
>> +	struct swnode *swnode = to_swnode(fwnode);
>> +	int ret;
>> +
>> +	ret = kstrtou32(swnode->parent->node->name + 5, 10, &endpoint->port);
>> +	if (ret)
>> +		return ret;
>> +
>> +	endpoint->id = swnode->id;
>> +	endpoint->local_fwnode = fwnode;
>> +
>> +	return 0;
>> +}
>> +
>>  static const struct fwnode_operations software_node_ops = {
>>  	.get = software_node_get,
>>  	.put = software_node_put,
>> @@ -551,7 +655,11 @@ static const struct fwnode_operations software_node_ops = {
>>  	.get_parent = software_node_get_parent,
>>  	.get_next_child_node = software_node_get_next_child,
>>  	.get_named_child_node = software_node_get_named_child_node,
>> -	.get_reference_args = software_node_get_reference_args
>> +	.get_reference_args = software_node_get_reference_args,
>> +	.graph_get_next_endpoint = software_node_graph_get_next_endpoint,
>> +	.graph_get_remote_endpoint = software_node_graph_get_remote_endpoint,
>> +	.graph_get_port_parent = software_node_graph_get_port_parent,
>> +	.graph_parse_endpoint = software_node_graph_parse_endpoint,
>>  };
>>  
>>  /* -------------------------------------------------------------------------- */
>
Daniel Scally Dec. 18, 2020, 10:26 p.m. UTC | #7
On 18/12/2020 20:37, Andy Shevchenko wrote:
> On Thu, Dec 17, 2020 at 11:43:31PM +0000, Daniel Scally wrote:
>> From: Heikki Krogerus <heikki.krogerus@linux.intel.com>
>>
>> This implements the remaining .graph_* callbacks in the
>> fwnode operations structure for the software nodes. That makes
>> the fwnode_graph*() functions available in the drivers also
>> when software nodes are used.
>>
>> The implementation tries to mimic the "OF graph" as much as
>> possible, but there is no support for the "reg" device
>> property. The ports will need to have the index in their
>> name which starts with "port@" (for example "port@0", "port@1",
>> ...) and endpoints will use the index of the software node
>> that is given to them during creation. The port nodes can
>> also be grouped under a specially named "ports" subnode,
>> just like in DT, if necessary.
>>
>> The remote-endpoints are reference properties under the
>> endpoint nodes that are named "remote-endpoint".
> 
> ...
> 
>> +	while ((port = software_node_get_next_child(parent, old))) {
>> +		if (!strncmp(to_swnode(port)->node->name, "port", 4))
>> +			return port;
>> +		old = port;
>> +	}
> 
> Dunno if we need defines for port and its length here.

Mmm, maybe a comment?

> ...
> 
>> +	ret = kstrtou32(swnode->parent->node->name + 5, 10, &endpoint->port);
> 
> But here at least comment is needed what 5 means ('port@' I suppose).

Ack - I'll add an explanatory comment (and yep, it's 'port@')

>> +	if (ret)
>> +		return ret;
> 
>
Daniel Scally Dec. 18, 2020, 11:46 p.m. UTC | #8
On 18/12/2020 22:13, Daniel Scally wrote:

>>> +			break;
>>> +		}
>>> +
>>> +		/* No more endpoints for that port, so stop passing old */
>>> +		old = NULL;
>>
>> I wonder if you could drop the 'old' variable and use 'enpoint' in the
>> call to software_node_get_next_child(). You could then drop these two
>> lines.
> 
> That won't work, because endpoint would at that point not be a child of
> the port we're passing, and the function relies on it being one:
> 
> 	if (!p || list_empty(&p->children) ||
> 	    (c && list_is_last(&c->entry, &p->children))) {
> 		fwnode_handle_put(child);
> 		return NULL;
> 	}
> 

Wait, that's nonsense of course, because endpoint gets set to NULL when
software_node_get_next_child() finds nothing - I'll double check but
pretty sure you're right.
Daniel Scally Dec. 18, 2020, 11:57 p.m. UTC | #9
Hi Laurent - thanks for the comments

On 18/12/2020 16:53, Laurent Pinchart wrote:
>> +static void cio2_bridge_init_property_names(struct cio2_sensor *sensor)
>> +{
>> +	strscpy(sensor->prop_names.clock_frequency, "clock-frequency",
>> +		sizeof(sensor->prop_names.clock_frequency));
>> +	strscpy(sensor->prop_names.rotation, "rotation",
>> +		sizeof(sensor->prop_names.rotation));
>> +	strscpy(sensor->prop_names.bus_type, "bus-type",
>> +		sizeof(sensor->prop_names.bus_type));
>> +	strscpy(sensor->prop_names.data_lanes, "data-lanes",
>> +		sizeof(sensor->prop_names.data_lanes));
>> +	strscpy(sensor->prop_names.remote_endpoint, "remote-endpoint",
>> +		sizeof(sensor->prop_names.remote_endpoint));
>> +	strscpy(sensor->prop_names.link_frequencies, "link-frequencies",
>> +		sizeof(sensor->prop_names.link_frequencies));
> 
> Just curious, was there anything not working correctly with the proposal
> I made ?
> 
> static const struct cio2_property_names prop_names = {
> 	.clock_frequency = "clock-frequency",
> 	.rotation = "rotation",
> 	.bus_type = "bus-type",
> 	.data_lanes = "data-lanes",
> 	.remote_endpoint = "remote-endpoint",
> };
> 
> static void cio2_bridge_init_property_names(struct cio2_sensor *sensor)
> {
> 	sensor->prop_names = prop_names;
> }
> 
> It generates a warning when the string is too long for the field size,
> which should help catching issues at compilation time.

Yes, though I don't know how much of a real-world problem it would have
been - if you recall we have the issue that the device grabs a reference
to the software_nodes (after we stopped delaying until after the
i2c_client is available), which means we can't safely free the
cio2_bridge struct on module unload. That also means we can't rely on
those pointers to string literals existing, because if the ipu3-cio2
module gets unloaded they'll be gone.

Shame, as it's way neater.

>> +static void cio2_bridge_init_swnode_names(struct cio2_sensor *sensor)
>> +{
>> +	snprintf(sensor->node_names.remote_port, 7, "port@%u", sensor->ssdb.link);
>> +	strscpy(sensor->node_names.port, "port@0", sizeof(sensor->node_names.port));
>> +	strscpy(sensor->node_names.endpoint, "endpoint@0", sizeof(sensor->node_names.endpoint));
> 
> I'd wrap lines, but maybe that's because I'm an old-school, 80-columns
> programmer :-)

Heh sure, I'll wrap them.

>> +static int cio2_bridge_connect_sensors(struct cio2_bridge *bridge,
>> +				       struct pci_dev *cio2)
>> +{
>> +	struct fwnode_handle *fwnode;
>> +	struct cio2_sensor *sensor;
>> +	struct acpi_device *adev;
>> +	unsigned int i;
>> +	int ret = 0;
>> +
>> +	for (i = 0; i < ARRAY_SIZE(cio2_supported_sensors); i++) {
>> +		const struct cio2_sensor_config *cfg = &cio2_supported_sensors[i];
>> +
>> +		for_each_acpi_dev_match(adev, cfg->hid, NULL, -1) {
>> +			if (bridge->n_sensors >= CIO2_NUM_PORTS) {
>> +				dev_warn(&cio2->dev, "Exceeded available CIO2 ports\n");
>> +				/* overflow i so outer loop ceases */
>> +				i = ARRAY_SIZE(cio2_supported_sensors);
>> +				break;
> 
> Or just
> 
> 				return 0;
> 
> ?

Derp, yes of course.


>> +/* Data representation as it is in ACPI SSDB buffer */
>> +struct cio2_sensor_ssdb {
>> +	u8 version;				/* 0000 */
>> +	u8 sku;					/* 0001 */
>> +	u8 guid_csi2[16];			/* 0002 */
>> +	u8 devfunction;				/* 0003 */
>> +	u8 bus;					/* 0004 */
>> +	u32 dphylinkenfuses;			/* 0005 */
>> +	u32 clockdiv;				/* 0009 */
>> +	u8 link;				/* 0013 */
>> +	u8 lanes;				/* 0014 */
>> +	u32 csiparams[10];			/* 0015 */
>> +	u32 maxlanespeed;			/* 0019 */
>> +	u8 sensorcalibfileidx;			/* 0023 */
>> +	u8 sensorcalibfileidxInMBZ[3];		/* 0024 */
>> +	u8 romtype;				/* 0025 */
>> +	u8 vcmtype;				/* 0026 */
>> +	u8 platforminfo;			/* 0027 */
> 
> Why stop at 27 ? :-) I'd either go all the way, or not at all. It's also
> quite customary to represent offset as hex values, as that's what most
> hex editors / viewers will show.

Oops - that was actually just me debugging...I guess I might actually
finish it, converted to hex. It came in useful reading the DSDT to have
that somewhere easy to refer to.

> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

Nice - thank you!
Daniel Scally Dec. 19, 2020, 12:22 a.m. UTC | #10
Hi Andy, thanks for the comments

On 18/12/2020 21:17, Andy Shevchenko wrote:
> On Thu, Dec 17, 2020 at 11:43:37PM +0000, Daniel Scally wrote:
>> Currently on platforms designed for Windows, connections between CIO2 and
>> sensors are not properly defined in DSDT. This patch extends the ipu3-cio2
>> driver to compensate by building software_node connections, parsing the
>> connection properties from the sensor's SSDB buffer.
> 
> ...
> 
>> +	sensor->ep_properties[0] = PROPERTY_ENTRY_U32(sensor->prop_names.bus_type, 4);
> 
> Does 4 has any meaning that can be described by #define ?

It's V4L2_FWNODE_BUS_TYPE_CSI2_DPHY:

https://elixir.bootlin.com/linux/latest/source/drivers/media/v4l2-core/v4l2-fwnode.c#L36

That enum's not in an accessible header, but I can define it in this
module's header

>> +static void cio2_bridge_init_swnode_names(struct cio2_sensor *sensor)
>> +{
>> +	snprintf(sensor->node_names.remote_port, 7, "port@%u", sensor->ssdb.link);
> 
> Hmm... I think you should use actual size of remote_port instead of 7.

Yes ok


>> +	strscpy(sensor->node_names.port, "port@0", sizeof(sensor->node_names.port));
> 
> Yeah, I would rather like to see one point of the definition of the format.
> If it's the same as per OF case, perhaps some generic header (like fwnode.h?) is good for this?
> In this case the 5 in one of the previous patches Also can be derived from the format.

Okedokey. It is indeed intended to match OF and ACPI case, both of which
mandate that format (though only ACPI's functions seem to enforce it).
fwnode.h seems as good a place as any to me, though I'm not sure there's
anywhere in the driver code for OF or ACPI that would actually use it at
the moment.

>> +	strscpy(sensor->node_names.endpoint, "endpoint@0", sizeof(sensor->node_names.endpoint));
> 
> Similar here.
> 
>> +}
> 
> ...
> 
>> +	for (i = 0; i < ARRAY_SIZE(cio2_supported_sensors); i++) {
>> +		const struct cio2_sensor_config *cfg = &cio2_supported_sensors[i];
>> +
>> +		for_each_acpi_dev_match(adev, cfg->hid, NULL, -1) {
> 
>> +			if (bridge->n_sensors >= CIO2_NUM_PORTS) {
>> +				dev_warn(&cio2->dev, "Exceeded available CIO2 ports\n");
> 
>> +				/* overflow i so outer loop ceases */
>> +				i = ARRAY_SIZE(cio2_supported_sensors);
>> +				break;
> 
> Why not to create a new label below and assign ret here with probably comment
> why it's not an error?

Sure, I can do that, but since it wouldn't need any cleanup I could also
just return 0 here as Laurent suggest (but with a comment explaining why
that's ok as you say) - do you have a preference?

>> +			}
> 
> ...
> 
>> +			ret = cio2_bridge_read_acpi_buffer(adev, "SSDB",
>> +							   &sensor->ssdb,
>> +							   sizeof(sensor->ssdb));
>> +			if (ret < 0)
> 
> if (ret) (because positive case can be returned just by next conditional).

cio2_bridge_read_acpi_buffer() returns the buffer length on success at
the moment, but I can change it to return 0 and have this be if (ret)

>> +				goto err_put_adev;
>> +
>> +			if (sensor->ssdb.lanes > 4) {
>> +				dev_err(&adev->dev,
>> +					"Number of lanes in SSDB is invalid\n");
>> +				goto err_put_adev;
>> +			}
> 
> ...
> 
>> +			dev_info(&cio2->dev, "Found supported sensor %s\n",
>> +				 acpi_dev_name(adev));
>> +
>> +			bridge->n_sensors++;
>> +		}
>> +	}
> 
> 	return 0;

Okedokey

> 
>> +err_free_swnodes:
>> +	software_node_unregister_nodes(sensor->swnodes);
>> +err_put_adev:
>> +	acpi_dev_put(sensor->adev);
> 
> err_out:

Depends on question above I think

>> +	return ret;
>> +}
> 
> ...
> 
>> +enum cio2_sensor_swnodes {
>> +	SWNODE_SENSOR_HID,
>> +	SWNODE_SENSOR_PORT,
>> +	SWNODE_SENSOR_ENDPOINT,
>> +	SWNODE_CIO2_PORT,
>> +	SWNODE_CIO2_ENDPOINT,
> 
>> +	NR_OF_SENSOR_SWNODES
> 
> Perhaps same namespace, i.e.
> 
> 	SWNODE_SENSOR_NR

Yep, will do.

Thanks
Dan
Andy Shevchenko Dec. 19, 2020, 6:52 p.m. UTC | #11
On Sat, Dec 19, 2020 at 2:25 AM Daniel Scally <djrscally@gmail.com> wrote:
> On 18/12/2020 21:17, Andy Shevchenko wrote:
> > On Thu, Dec 17, 2020 at 11:43:37PM +0000, Daniel Scally wrote:

...

> >> +    sensor->ep_properties[0] = PROPERTY_ENTRY_U32(sensor->prop_names.bus_type, 4);
> >
> > Does 4 has any meaning that can be described by #define ?
>
> It's V4L2_FWNODE_BUS_TYPE_CSI2_DPHY:
>
> https://elixir.bootlin.com/linux/latest/source/drivers/media/v4l2-core/v4l2-fwnode.c#L36
>
> That enum's not in an accessible header, but I can define it in this
> module's header

Maybe you can do a preparatory patch to make it visible to v4l2
drivers? (Like moving to one of v4l2 headers)

...

> >> +                    if (bridge->n_sensors >= CIO2_NUM_PORTS) {
> >> +                            dev_warn(&cio2->dev, "Exceeded available CIO2 ports\n");
> >
> >> +                            /* overflow i so outer loop ceases */
> >> +                            i = ARRAY_SIZE(cio2_supported_sensors);
> >> +                            break;
> >
> > Why not to create a new label below and assign ret here with probably comment
> > why it's not an error?
>
> Sure, I can do that, but since it wouldn't need any cleanup I could also
> just return 0 here as Laurent suggest (but with a comment explaining why
> that's ok as you say) - do you have a preference?

While it's a good suggestion it will bring a bit of inconsistency into
approach. Everywhere else in the function you are using the goto
approach.
So yes, I have a preference.

> >> +                    }

...

> >> +                    ret = cio2_bridge_read_acpi_buffer(adev, "SSDB",
> >> +                                                       &sensor->ssdb,
> >> +                                                       sizeof(sensor->ssdb));
> >> +                    if (ret < 0)
> >
> > if (ret) (because positive case can be returned just by next conditional).
>
> cio2_bridge_read_acpi_buffer() returns the buffer length on success at
> the moment, but I can change it to return 0 and have this be if (ret)

Please correct this somehow, because the next failure returns it
instead of error...

> >> +                            goto err_put_adev;
> >> +
> >> +                    if (sensor->ssdb.lanes > 4) {
> >> +                            dev_err(&adev->dev,
> >> +                                    "Number of lanes in SSDB is invalid\n");

...I'm even thinking that you have to assign ret here to something meaningful.

> >> +                            goto err_put_adev;
> >> +                    }
Daniel Scally Dec. 19, 2020, 11:24 p.m. UTC | #12
On 19/12/2020 00:39, Laurent Pinchart wrote:
> Hi Daniel,
> 
> On Fri, Dec 18, 2020 at 11:57:54PM +0000, Daniel Scally wrote:
>> Hi Laurent - thanks for the comments
>>
>> On 18/12/2020 16:53, Laurent Pinchart wrote:
>>>> +static void cio2_bridge_init_property_names(struct cio2_sensor *sensor)
>>>> +{
>>>> +	strscpy(sensor->prop_names.clock_frequency, "clock-frequency",
>>>> +		sizeof(sensor->prop_names.clock_frequency));
>>>> +	strscpy(sensor->prop_names.rotation, "rotation",
>>>> +		sizeof(sensor->prop_names.rotation));
>>>> +	strscpy(sensor->prop_names.bus_type, "bus-type",
>>>> +		sizeof(sensor->prop_names.bus_type));
>>>> +	strscpy(sensor->prop_names.data_lanes, "data-lanes",
>>>> +		sizeof(sensor->prop_names.data_lanes));
>>>> +	strscpy(sensor->prop_names.remote_endpoint, "remote-endpoint",
>>>> +		sizeof(sensor->prop_names.remote_endpoint));
>>>> +	strscpy(sensor->prop_names.link_frequencies, "link-frequencies",
>>>> +		sizeof(sensor->prop_names.link_frequencies));
>>>
>>> Just curious, was there anything not working correctly with the proposal
>>> I made ?
>>>
>>> static const struct cio2_property_names prop_names = {
>>> 	.clock_frequency = "clock-frequency",
>>> 	.rotation = "rotation",
>>> 	.bus_type = "bus-type",
>>> 	.data_lanes = "data-lanes",
>>> 	.remote_endpoint = "remote-endpoint",
>>> };
>>>
>>> static void cio2_bridge_init_property_names(struct cio2_sensor *sensor)
>>> {
>>> 	sensor->prop_names = prop_names;
>>> }
>>>
>>> It generates a warning when the string is too long for the field size,
>>> which should help catching issues at compilation time.
>>
>> Yes, though I don't know how much of a real-world problem it would have
>> been - if you recall we have the issue that the device grabs a reference
>> to the software_nodes (after we stopped delaying until after the
>> i2c_client is available), which means we can't safely free the
>> cio2_bridge struct on module unload. That also means we can't rely on
>> those pointers to string literals existing, because if the ipu3-cio2
>> module gets unloaded they'll be gone.
> 
> But the strings above are not stored as literals in .rodata, they're
> copied in prop_names (itself in .rodata), which is then copied to
> sensor->prop_names.

Yeah, my bad; I also had changed the struct definition to:

struct cio2_property_names {
	char *clock_frequency;
	...
};

And that behaves differently - apologies. I'll change to your proposal.
Daniel Scally Dec. 19, 2020, 11:48 p.m. UTC | #13
On 19/12/2020 18:52, Andy Shevchenko wrote:
> On Sat, Dec 19, 2020 at 2:25 AM Daniel Scally <djrscally@gmail.com> wrote:
>> On 18/12/2020 21:17, Andy Shevchenko wrote:
>>> On Thu, Dec 17, 2020 at 11:43:37PM +0000, Daniel Scally wrote:
> 
> ...
> 
>>>> +    sensor->ep_properties[0] = PROPERTY_ENTRY_U32(sensor->prop_names.bus_type, 4);
>>>
>>> Does 4 has any meaning that can be described by #define ?
>>
>> It's V4L2_FWNODE_BUS_TYPE_CSI2_DPHY:
>>
>> https://elixir.bootlin.com/linux/latest/source/drivers/media/v4l2-core/v4l2-fwnode.c#L36
>>
>> That enum's not in an accessible header, but I can define it in this
>> module's header
> 
> Maybe you can do a preparatory patch to make it visible to v4l2
> drivers? (Like moving to one of v4l2 headers)

Sure ok, guess media/v4l2-fwnode.h makes the most sense.

> ...
> 
>>>> +                    if (bridge->n_sensors >= CIO2_NUM_PORTS) {
>>>> +                            dev_warn(&cio2->dev, "Exceeded available CIO2 ports\n");
>>>
>>>> +                            /* overflow i so outer loop ceases */
>>>> +                            i = ARRAY_SIZE(cio2_supported_sensors);
>>>> +                            break;
>>>
>>> Why not to create a new label below and assign ret here with probably comment
>>> why it's not an error?
>>
>> Sure, I can do that, but since it wouldn't need any cleanup I could also
>> just return 0 here as Laurent suggest (but with a comment explaining why
>> that's ok as you say) - do you have a preference?
> 
> While it's a good suggestion it will bring a bit of inconsistency into
> approach. Everywhere else in the function you are using the goto
> approach.
> So yes, I have a preference.

No problem

>>>> +                    }
> 
> ...
> 
>>>> +                    ret = cio2_bridge_read_acpi_buffer(adev, "SSDB",
>>>> +                                                       &sensor->ssdb,
>>>> +                                                       sizeof(sensor->ssdb));
>>>> +                    if (ret < 0)
>>>
>>> if (ret) (because positive case can be returned just by next conditional).
>>
>> cio2_bridge_read_acpi_buffer() returns the buffer length on success at
>> the moment, but I can change it to return 0 and have this be if (ret)
> 
> Please correct this somehow, because the next failure returns it
> instead of error...

Ah! Good spot - thank you. I will fix that yes.

>>>> +                            goto err_put_adev;
>>>> +
>>>> +                    if (sensor->ssdb.lanes > 4) {
>>>> +                            dev_err(&adev->dev,
>>>> +                                    "Number of lanes in SSDB is invalid\n");
> 
> ...I'm even thinking that you have to assign ret here to something meaningful.

Yeah I agree, I will do this too.

>>>> +                            goto err_put_adev;
>>>> +                    }
>
Sakari Ailus Dec. 21, 2020, 10:57 a.m. UTC | #14
On Mon, Dec 21, 2020 at 10:52:52AM +0000, Daniel Scally wrote:
> 
> On 21/12/2020 10:21, Sakari Ailus wrote:
> > Hi Daniel, Andy,
> >
> > On Sat, Dec 19, 2020 at 11:48:51PM +0000, Daniel Scally wrote:
> >> On 19/12/2020 18:52, Andy Shevchenko wrote:
> >>> On Sat, Dec 19, 2020 at 2:25 AM Daniel Scally <djrscally@gmail.com> wrote:
> >>>> On 18/12/2020 21:17, Andy Shevchenko wrote:
> >>>>> On Thu, Dec 17, 2020 at 11:43:37PM +0000, Daniel Scally wrote:
> >>> ...
> >>>
> >>>>>> +    sensor->ep_properties[0] = PROPERTY_ENTRY_U32(sensor->prop_names.bus_type, 4);
> >>>>> Does 4 has any meaning that can be described by #define ?
> >>>> It's V4L2_FWNODE_BUS_TYPE_CSI2_DPHY:
> >>>>
> >>>> https://elixir.bootlin.com/linux/latest/source/drivers/media/v4l2-core/v4l2-fwnode.c#L36
> >>>>
> >>>> That enum's not in an accessible header, but I can define it in this
> >>>> module's header
> >>> Maybe you can do a preparatory patch to make it visible to v4l2
> >>> drivers? (Like moving to one of v4l2 headers)
> >> Sure ok, guess media/v4l2-fwnode.h makes the most sense.
> > Yes, please.
> Done for the next version
> >
> >>> ...
> >>>
> >>>>>> +                    if (bridge->n_sensors >= CIO2_NUM_PORTS) {
> >>>>>> +                            dev_warn(&cio2->dev, "Exceeded available CIO2 ports\n");
> >>>>>> +                            /* overflow i so outer loop ceases */
> >>>>>> +                            i = ARRAY_SIZE(cio2_supported_sensors);
> >>>>>> +                            break;
> >>>>> Why not to create a new label below and assign ret here with probably comment
> >>>>> why it's not an error?
> >>>> Sure, I can do that, but since it wouldn't need any cleanup I could also
> >>>> just return 0 here as Laurent suggest (but with a comment explaining why
> >>>> that's ok as you say) - do you have a preference?
> >>> While it's a good suggestion it will bring a bit of inconsistency into
> >>> approach. Everywhere else in the function you are using the goto
> >>> approach.
> >>> So yes, I have a preference.
> >> No problem
> > Laurent also commented on the return code.
> >
> > I might just handle this as an error. The earlier ports are fine, but
> > there's also a problem with the data here. It'd be easier to spot that this
> > way, and we can change this in the future if need be.
> 
> 
> You mean just raise an error with dev_err()? Or fail the probe and
> unwind the 4 sensors that were already connected successfully? I'm fine

Both.

> with that if so - we have no in scope devices where that will be a
> problem at the moment.

I guess there will be quite a few additional things to address before
getting anything with four sensors working.