| Message ID | 20240427203650.582989-1-sui.jingfeng@linux.dev |
|---|---|
| State | New |
| Headers | show |
| Series | [v3] software node: Implement device_get_match_data fwnode callback | expand |
Hi Sui, On Sun, Apr 28, 2024 at 04:36:50AM +0800, Sui Jingfeng wrote: > Because the software node backend of the fwnode API framework lacks an > implementation for the .device_get_match_data function callback. This > makes it difficult to use(and/or test) a few drivers that originates > from DT world on the non-DT platform. > > Implement the .device_get_match_data fwnode callback, which helps to keep > the three backends of the fwnode API aligned as much as possible. This is > also a fundamental step to make a few drivers OF-independent truely > possible. > > Device drivers or platform setup codes are expected to provide a software > node string property, named as "compatible". At this moment, the value of > this string property is being used to match against the compatible entries > in the of_device_id table. It can be extended in the future though. I am sorry, but this is not really correct. Software nodes are used to augment missing or incomplete parameters, but are never primary objects in the matching process. Sometimes "compatible" property is used with software nodes, but it does not participate in the matching process. There are several ways for various buses to match a device and a driver, but none of them operate on software nodes. Consider for example how devices on SPI bus are matched (see drivers/spi/spi.c::spi_match_device()): 1. OF/device tree based match. It *requires* the device to have dev->of_node which is coming from a DTB. It does not work on software nodes. In case of match the match data should come from of_device_id entry. 2. ACPI-based match. The match is done based either on OF-compatible data (which includes "compatible" property) in _DSD (if driver supports OF-based matching), or based on HID/CID data. In the latter case the match data is coming from acpi_device_id entry. 3. Name-based match, typically used for board-instantiated devices. In this case match is done by comparing device name under which it was instantiated against names listed in the drivers id_table. The match data is coming from spi_device_id entry. Similar matching processes are implemented for i2c and platform buses, as well as others. Your patch is effectively hijacks the #3 matching process and substitutes the bus-specific match data (from spi_device_id/i2c_device_id/etc) with OF data. This is not expected and while we may want this in a long term (so we can eventually remove these bus-specific device ids and only have ACPI/OF ones) I do not think we are ready for this yet. At the very least this needs to be very clearly documented. > > Fixes: ffb42e64561e ("drm/tiny/repaper: Make driver OF-independent") > Fixes: 5703d6ae9573 ("drm/tiny/st7735r: Make driver OF-independent") As other people mentioned this patch does not fix the aforementioned commits because they are not broken. In case of non-OF match (which includes the case where you use software nodes) the match data is coming from matching spi_device_id entry in the driver. Thanks.
Hi, On 6/22/24 03:58, Dmitry Torokhov wrote: > Hi Sui, > > On Sun, Apr 28, 2024 at 04:36:50AM +0800, Sui Jingfeng wrote: >> Because the software node backend of the fwnode API framework lacks an >> implementation for the .device_get_match_data function callback. This >> makes it difficult to use(and/or test) a few drivers that originates >> from DT world on the non-DT platform. >> >> Implement the .device_get_match_data fwnode callback, which helps to keep >> the three backends of the fwnode API aligned as much as possible. This is >> also a fundamental step to make a few drivers OF-independent truely >> possible. >> >> Device drivers or platform setup codes are expected to provide a software >> node string property, named as "compatible". At this moment, the value of >> this string property is being used to match against the compatible entries >> in the of_device_id table. It can be extended in the future though. > > I am sorry, but this is not really correct. I fine if the maintainers of fwnode API want to reject this, but got rejected is not really equals to "not correct". Software nodes are used to > augment missing or incomplete parameters, but are never primary objects > in the matching process. Sometimes "compatible" property is used with > software nodes, but it does not participate in the matching process. > There are several ways for various buses to match a device and a driver, > but none of them operate on software nodes. It's not participate in the matching process in the *past*, but what we present is something *new*. I fine if you adhere to *old* and/or *subsystem-dependent* approach, but there really no need to persuade other people to follow your "old" idea. Consider for example how > devices on SPI bus are matched (see > drivers/spi/spi.c::spi_match_device()): This only make the driver be able to probed in a non-DT way, but it doesn't tell how does the *additional device properties* can be get. This is the key point. > 1. OF/device tree based match. It *requires* the device to have > dev->of_node which is coming from a DTB. It does not work on software > nodes. In case of match the match data should come from of_device_id > entry. > > 2. ACPI-based match. The match is done based either on OF-compatible > data (which includes "compatible" property) in _DSD (if driver supports > OF-based matching), or based on HID/CID data. In the latter case the > match data is coming from acpi_device_id entry. > > 3. Name-based match, typically used for board-instantiated devices. In > this case match is done by comparing device name under which it was > instantiated against names listed in the drivers id_table. The match > data is coming from spi_device_id entry. The statements here sound right, but it's useless. Because the problems isn't solved yet, nor does you words point out a practical approach. > Similar matching processes are implemented for i2c and platform buses, > as well as others. > > Your patch is effectively hijacks the #3 matching process and > substitutes the bus-specific match data (from > spi_device_id/i2c_device_id/etc) with OF data. This is not expected and Please stop *contaminating* other people's patch, if you have better idea you can posting it. My patch open a new door, and there do have programmer in requesting(need) this in the past. > while we may want this in a long term (so we can eventually remove these > bus-specific device ids and only have ACPI/OF ones) I do not think we > are ready for this yet. At the very least this needs to be very clearly > documented. This is your *personal* wants, if you want to remove something, just do it. Keep quiet if you are not ready. Exposing your concerns doesn't help to solve any problems. Or, if you want it to be clear, you can contribute to Documentation/ gpu/todo.rst. Other peoples help you to become clear there, thanks. Please note that we are talking about the completeness of the fwnode APIs, what's you say above has nothing to do the device fwnode APIs. Hence, is not revelant to my patch, again is out of scope. >> >> Fixes: ffb42e64561e ("drm/tiny/repaper: Make driver OF-independent") >> Fixes: 5703d6ae9573 ("drm/tiny/st7735r: Make driver OF-independent") > > As other people mentioned this patch does not fix the aforementioned > commits because they are not broken. You still not really understand what other people does, I'm not saying it broken. I'm talking about the completeness. In case of non-OF match (which > includes the case where you use software nodes) the match data is coming > from matching spi_device_id entry in the driver. We don't care about much how it is probed now, rather, after the driver probed by a non-OF way, how does the additional devices properties can be get? Say: 1) "device_property_read_u32(dev, "rotation", &rotation);" and 2) "!device_property_read_string(dev, "pervasive,thermal-zone", &thermal_zone))" For those spi/i2c/platform devices, what we argues are that those drivers really should just depend on "OF" before we have a reliable fwnode API backend to redirect to. Where the additional device_property_read_xxxx() calls redirect to? What if users want to invoke more device_property_read_xxxx() function?
On Sun, Jun 23, 2024 at 02:04:00AM +0800, Sui Jingfeng wrote: > Hi, > > On 6/22/24 03:58, Dmitry Torokhov wrote: > > Hi Sui, > > > > On Sun, Apr 28, 2024 at 04:36:50AM +0800, Sui Jingfeng wrote: > > > Because the software node backend of the fwnode API framework lacks an > > > implementation for the .device_get_match_data function callback. This > > > makes it difficult to use(and/or test) a few drivers that originates > > > from DT world on the non-DT platform. > > > > > > Implement the .device_get_match_data fwnode callback, which helps to keep > > > the three backends of the fwnode API aligned as much as possible. This is > > > also a fundamental step to make a few drivers OF-independent truely > > > possible. > > > > > > Device drivers or platform setup codes are expected to provide a software > > > node string property, named as "compatible". At this moment, the value of > > > this string property is being used to match against the compatible entries > > > in the of_device_id table. It can be extended in the future though. > > > > I am sorry, but this is not really correct. > > I fine if the maintainers of fwnode API want to reject this, but got > rejected is not really equals to "not correct". Your statement is factually incorrect. As I shown below using SPI bus as an example, compatible is only used for OF-based matches. Specifying "compatible" property via SW node does zilch for matching process. There are drivers like atmel_mxt_ts that check presence of "compatible" explicitly (I added it to ensure that the touch controller has all necessary properties on x86 because older Chromebooks were using ACPI HID names to differentiate between the touchscreen and touchpad and I wanted something more robust) but this is not a part of the matching process. > > Software nodes are used to > > augment missing or incomplete parameters, but are never primary objects > > in the matching process. Sometimes "compatible" property is used with > > software nodes, but it does not participate in the matching process. > There are several ways for various buses to match a device and a driver, > > but none of them operate on software nodes. > > It's not participate in the matching process in the *past*, but what > we present is something *new*. I see absolutely nothing in your patch that would affect the matching process. It is also not a part of a larger series, so there is nothing "new" here. > I fine if you adhere to *old* and/or > *subsystem-dependent* approach, but there really no need to persuade > other people to follow your "old" idea. > > Consider for example how > > devices on SPI bus are matched (see > > drivers/spi/spi.c::spi_match_device()): > > > This only make the driver be able to probed in a non-DT way, but > it doesn't tell how does the *additional device properties* can > be get. This is the key point. I think you misunderstand what device_get_match_data() does. It does not deal with device properties so there's nothing "additional" there. > > > > 1. OF/device tree based match. It *requires* the device to have > > dev->of_node which is coming from a DTB. It does not work on software > > nodes. In case of match the match data should come from of_device_id > > entry. > > > > 2. ACPI-based match. The match is done based either on OF-compatible > > data (which includes "compatible" property) in _DSD (if driver supports > > OF-based matching), or based on HID/CID data. In the latter case the > > match data is coming from acpi_device_id entry. > > > > 3. Name-based match, typically used for board-instantiated devices. In > > this case match is done by comparing device name under which it was > > instantiated against names listed in the drivers id_table. The match > > data is coming from spi_device_id entry. > > The statements here sound right, but it's useless. Because the problems > isn't solved yet, nor does you words point out a practical approach. I am explaining you how the system works since there appears to be a severe misconnect. I think you need to state clearly the problem you are trying to solve, beyond "completeness of the API" argument. > > > Similar matching processes are implemented for i2c and platform buses, > > as well as others. > > > > Your patch is effectively hijacks the #3 matching process and > > substitutes the bus-specific match data (from > > spi_device_id/i2c_device_id/etc) with OF data. This is not expected and > > Please stop *contaminating* other people's patch, if you have better I am providing a review of your proposal/patch. That is what happens on LKML and I suggest you get used to this if you want to become a regular contributor to the Linxu kernel. > idea you can posting it. My patch open a new door, and there do have > programmer in requesting(need) this in the past. Please point at what exactly you are trying to solve here, because it is still not clear. Start from the beginning. What are you trying to achieve on a practical level? I.e. "If I do *this* my device does not work because of *reason* and to fix this I need *that*". It may very well be that right "that" is something different from what you are proposing, > > > > while we may want this in a long term (so we can eventually remove these > > bus-specific device ids and only have ACPI/OF ones) I do not think we > > are ready for this yet. At the very least this needs to be very clearly > > documented. > > This is your *personal* wants, if you want to remove something, > just do it. Keep quiet if you are not ready. Exposing your concerns > doesn't help to solve any problems. This sounds incredibly rude. Please consider your tone when writing your responses. > > Or, if you want it to be clear, you can contribute to Documentation/ > gpu/todo.rst. Other peoples help you to become clear there, thanks. > > Please note that we are talking about the completeness of the fwnode > APIs, what's you say above has nothing to do the device fwnode APIs. > Hence, is not revelant to my patch, again is out of scope. > > > > > > > Fixes: ffb42e64561e ("drm/tiny/repaper: Make driver OF-independent") > > > Fixes: 5703d6ae9573 ("drm/tiny/st7735r: Make driver OF-independent") > > > > As other people mentioned this patch does not fix the aforementioned > > commits because they are not broken. > > You still not really understand what other people does, I'm not saying > it broken. I'm talking about the completeness. Completeness for the sake of completeness is not an argument. As it stands your patch will not change these driver's behavior. > > In case of non-OF match (which > > includes the case where you use software nodes) the match data is coming > > from matching spi_device_id entry in the driver. > > > We don't care about much how it is probed now, rather, after the driver > probed by a non-OF way, how does the additional devices properties > can be get? > > > Say: > > 1) "device_property_read_u32(dev, "rotation", &rotation);" and > 2) "!device_property_read_string(dev, "pervasive,thermal-zone", > &thermal_zone))" > > > For those spi/i2c/platform devices, what we argues are that > those drivers really should just depend on "OF" before we have > a reliable fwnode API backend to redirect to. They are working fine without such restriction now, so I see absolutely no reason imposing this restriction. > > Where the additional device_property_read_xxxx() calls redirect to? > > What if users want to invoke more device_property_read_xxxx() function? They are being directed to first the primary FW node instance, which may be either OF, ACPI, or SW node, and then, if property is not present there, to the secondary FW node, which can be either again. At no point ->device_get_match_data() callback in involved in this process. Thanks.
Hi, On 6/23/24 03:29, Dmitry Torokhov wrote: >> In case of non-OF match (which >>> includes the case where you use software nodes) the match data is coming >>> from matching spi_device_id entry in the driver. >> >> We don't care about much how it is probed now, rather, after the driver >> probed by a non-OF way, how does the additional devices properties >> can be get? >> >> >> Say: >> >> 1) "device_property_read_u32(dev, "rotation", &rotation);" and >> 2) "!device_property_read_string(dev, "pervasive,thermal-zone", >> &thermal_zone))" >> >> >> For those spi/i2c/platform devices, what we argues are that >> those drivers really should just depend on "OF" before we have >> a reliable fwnode API backend to redirect to. > They are working fine without such restriction now, You still *NOT* answer where the additional devices properties[1][2] can be acquire. [1] device_property_read_u32(dev, "rotation", &rotation) [2] device_property_read_string(dev, "pervasive,thermal-zone", &thermal_zone)) > so I see absolutely no reason imposing this restriction. The reason is rigorous. You are acclaiming that works by hardcode or by ignoring the flaws is fine, then all driver are working fine by *your* standard. Your personal standard has nothing to do with this patch. >> Where the additional device_property_read_xxxx() calls redirect to? >> >> What if users want to invoke more device_property_read_xxxx() function? > They are being directed to first the primary FW node instance, which may > be either OF, ACPI, or SW node, and then, if property is not present > there, to the secondary FW node, which can be either again. What I'm asking is, on the non-OF and no-ACPI cases, where's those device_property_read_xxx() calls can be directed to? > At no point ->device_get_match_data() callback in involved in this > process. > The patch is written for people who need it, not for people who don't. It will be involved if the device is associated with software node. Its for fwnode API user to get a consistent experience, that is to get a matching data without introduce extra/duplicated match mechanism. The patch is focus on fixing the undefined behavior, is discussing the correct way to consolidate the fwnode API. Its not going to discuss how does the those *old" and/or how does those non-fwnode systems works. Its NOT discussing how does the driver itself can be probed, a driver can be probed multiple way and is another question. Being probed and extract matching data can two different thing and is perfectly valid. Your problem is that you are not fully understand what other people does before you rush into the discussion. You are putting restrictions onto other people, while leaving the problem itself there unsolved. Its not a place to express your personal value or you personal status, such as, you are "ready" or "not ready" for something. Or persuading somebody should get used to what or teaching people to talks with a whatever tone like a God. None of those junk words are technical, I can not see constructive ideas. Thanks.
diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c index eb6eb25b343b..b6f40715c4f8 100644 --- a/drivers/base/swnode.c +++ b/drivers/base/swnode.c @@ -15,6 +15,7 @@ #include <linux/kobject.h> #include <linux/kstrtox.h> #include <linux/list.h> +#include <linux/mod_devicetable.h> #include <linux/property.h> #include <linux/slab.h> #include <linux/spinlock.h> @@ -390,6 +391,33 @@ static void software_node_put(struct fwnode_handle *fwnode) kobject_put(&swnode->kobj); } +static const void * +software_node_get_match_data(const struct fwnode_handle *fwnode, + const struct device *dev) +{ + struct swnode *swnode = to_swnode(fwnode); + const struct of_device_id *matches = dev->driver->of_match_table; + const char *val = NULL; + int ret; + + ret = property_entry_read_string_array(swnode->node->properties, + "compatible", &val, 1); + if (ret < 0 || !val) + return NULL; + + if (!matches) + return NULL; + + while (matches->compatible[0]) { + if (!strcmp(matches->compatible, val)) + return matches->data; + + ++matches; + } + + return NULL; +} + static bool software_node_property_present(const struct fwnode_handle *fwnode, const char *propname) { @@ -676,6 +704,7 @@ software_node_graph_parse_endpoint(const struct fwnode_handle *fwnode, static const struct fwnode_operations software_node_ops = { .get = software_node_get, .put = software_node_put, + .device_get_match_data = software_node_get_match_data, .property_present = software_node_property_present, .property_read_int_array = software_node_read_int_array, .property_read_string_array = software_node_read_string_array,
Because the software node backend of the fwnode API framework lacks an implementation for the .device_get_match_data function callback. This makes it difficult to use(and/or test) a few drivers that originates from DT world on the non-DT platform. Implement the .device_get_match_data fwnode callback, which helps to keep the three backends of the fwnode API aligned as much as possible. This is also a fundamental step to make a few drivers OF-independent truely possible. Device drivers or platform setup codes are expected to provide a software node string property, named as "compatible". At this moment, the value of this string property is being used to match against the compatible entries in the of_device_id table. It can be extended in the future though. Fixes: ffb42e64561e ("drm/tiny/repaper: Make driver OF-independent") Fixes: 5703d6ae9573 ("drm/tiny/st7735r: Make driver OF-independent") Signed-off-by: Sui Jingfeng <sui.jingfeng@linux.dev> --- Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Daniel Scally <djrscally@gmail.com> Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com> Cc: Sakari Ailus <sakari.ailus@linux.intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> --- v1 -> v2: Update commit message v2 -> v3: Move a loop invariant conditional out of while clause --- drivers/base/swnode.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+)