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[v3,1/6] i2c: core: Setup i2c_adapter runtime-pm before calling device_add()

Message ID 20240621122503.10034-2-hdegoede@redhat.com
State Superseded
Headers show
Series i2c-i801 / dell-smo8800: Move instantiation of lis3lv02d i2c_client from i2c-i801 to dell-smo8800 | expand

Commit Message

Hans de Goede June 21, 2024, 12:24 p.m. UTC
Platform glue code, which is not build into the kernel and thus cannot
use i2c_register_board_info() may want to use bus_register_notifier()
to listen for i2c-adapters to show up on which the platform code needs
to manually instantiate platform specific i2c_clients.

This results in calling i2c_new_client_device() from the bus notifier
which happens near the device_add() call.

If the i2c-core has not yet setup runtime-pm (specifically the
no-callbacks and ignore-children flags) for the device embedded
inside struct i2c_adapter and the driver for the i2c_client
calls pm_runtime_set_active() this will trigger the following
error inside __pm_runtime_set_status():

"runtime PM trying to activate child device %s but parent (%s) is not active\n"

and the i2c_client's runtime-status will not be updated.

Split the device_register() call for the adapter into device_initialize()
and device_add() and move the pm-runtime init calls inbetween these 2 calls
so that the runtime-status can be correctly set when a driver binds from
the bus-notifier.

Note the moved pm-runtime init calls just override the initial value of
some flags in struct device set by device_initialize() and calling these
before device_add() is safe.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/i2c/i2c-core-base.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

Comments

Andy Shevchenko June 21, 2024, 3:08 p.m. UTC | #1
On Fri, Jun 21, 2024 at 2:25 PM Hans de Goede <hdegoede@redhat.com> wrote:
>
> Platform glue code, which is not build into the kernel and thus cannot
> use i2c_register_board_info() may want to use bus_register_notifier()
> to listen for i2c-adapters to show up on which the platform code needs
> to manually instantiate platform specific i2c_clients.
>
> This results in calling i2c_new_client_device() from the bus notifier
> which happens near the device_add() call.
>
> If the i2c-core has not yet setup runtime-pm (specifically the
> no-callbacks and ignore-children flags) for the device embedded
> inside struct i2c_adapter and the driver for the i2c_client
> calls pm_runtime_set_active() this will trigger the following
> error inside __pm_runtime_set_status():
>
> "runtime PM trying to activate child device %s but parent (%s) is not active\n"
>
> and the i2c_client's runtime-status will not be updated.
>
> Split the device_register() call for the adapter into device_initialize()
> and device_add() and move the pm-runtime init calls inbetween these 2 calls
> so that the runtime-status can be correctly set when a driver binds from
> the bus-notifier.
>
> Note the moved pm-runtime init calls just override the initial value of
> some flags in struct device set by device_initialize() and calling these
> before device_add() is safe.

LGTM, but this is non-trivial (I think) for the usual cases, can you
add a comment on top of the code you modified?

...

...somewhere here?

> +       res = device_add(&adap->dev);
>         if (res) {
>                 pr_err("adapter '%s': can't register device (%d)\n", adap->name, res);
>                 goto out_list;
diff mbox series

Patch

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index db0d1ac82910..fcb4696f1f93 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -1521,7 +1521,13 @@  static int i2c_register_adapter(struct i2c_adapter *adap)
 	dev_set_name(&adap->dev, "i2c-%d", adap->nr);
 	adap->dev.bus = &i2c_bus_type;
 	adap->dev.type = &i2c_adapter_type;
-	res = device_register(&adap->dev);
+	device_initialize(&adap->dev);
+	device_enable_async_suspend(&adap->dev);
+	pm_runtime_no_callbacks(&adap->dev);
+	pm_suspend_ignore_children(&adap->dev, true);
+	pm_runtime_enable(&adap->dev);
+
+	res = device_add(&adap->dev);
 	if (res) {
 		pr_err("adapter '%s': can't register device (%d)\n", adap->name, res);
 		goto out_list;
@@ -1533,11 +1539,6 @@  static int i2c_register_adapter(struct i2c_adapter *adap)
 	if (res)
 		goto out_reg;
 
-	device_enable_async_suspend(&adap->dev);
-	pm_runtime_no_callbacks(&adap->dev);
-	pm_suspend_ignore_children(&adap->dev, true);
-	pm_runtime_enable(&adap->dev);
-
 	res = i2c_init_recovery(adap);
 	if (res == -EPROBE_DEFER)
 		goto out_reg;