Hi Ricardo,
On Thu, Nov 10, 2022 at 03:11:43PM +0100, Ricardo Ribalda wrote:
> A driver that supports I2C_DRV_ACPI_WAIVE_D0_PROBE is not expected to
> power off a device that it has not powered on previously.
>
> For devices operating in "full_power" mode, the first call to
> `i2c_acpi_waive_d0_probe` will return 0, which means that the device
> will be turned on with `dev_pm_domain_attach`.
>
> If probe fails or the device is removed the second call to
> `i2c_acpi_waive_d0_probe` will return 1, which means that the device
> will not be turned off. This is, it will be left in a different power
> state. Lets fix it.
Good find.
I think this deserves to be applied to the stable tree. There are quite a
few kernel releases with the problem.
Reviewed-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
>
> Fixes: b18c1ad685d9 ("i2c: Allow an ACPI driver to manage the device's power state during probe")
> Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
>
> diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
> index b4edf10e8fd0..09a6bb89a352 100644
> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -467,6 +467,7 @@ static int i2c_device_probe(struct device *dev)
> {
> struct i2c_client *client = i2c_verify_client(dev);
> struct i2c_driver *driver;
> + bool do_power_on;
> int status;
>
> if (!client)
> @@ -545,8 +546,8 @@ static int i2c_device_probe(struct device *dev)
> if (status < 0)
> goto err_clear_wakeup_irq;
>
> - status = dev_pm_domain_attach(&client->dev,
> - !i2c_acpi_waive_d0_probe(dev));
> + do_power_on = !i2c_acpi_waive_d0_probe(dev);
> + status = dev_pm_domain_attach(&client->dev, do_power_on);
> if (status)
> goto err_clear_wakeup_irq;
>
> @@ -580,12 +581,14 @@ static int i2c_device_probe(struct device *dev)
> if (status)
> goto err_release_driver_resources;
>
> + client->turn_off_on_remove = do_power_on;
> +
> return 0;
>
> err_release_driver_resources:
> devres_release_group(&client->dev, client->devres_group_id);
> err_detach_pm_domain:
> - dev_pm_domain_detach(&client->dev, !i2c_acpi_waive_d0_probe(dev));
> + dev_pm_domain_detach(&client->dev, do_power_on);
> err_clear_wakeup_irq:
> dev_pm_clear_wake_irq(&client->dev);
> device_init_wakeup(&client->dev, false);
> @@ -610,7 +613,7 @@ static void i2c_device_remove(struct device *dev)
>
> devres_release_group(&client->dev, client->devres_group_id);
>
> - dev_pm_domain_detach(&client->dev, !i2c_acpi_waive_d0_probe(dev));
> + dev_pm_domain_detach(&client->dev, client->turn_off_on_remove);
>
> dev_pm_clear_wake_irq(&client->dev);
> device_init_wakeup(&client->dev, false);
> diff --git a/include/linux/i2c.h b/include/linux/i2c.h
> index f7c49bbdb8a1..412ac2b7cb2e 100644
> --- a/include/linux/i2c.h
> +++ b/include/linux/i2c.h
> @@ -326,6 +326,8 @@ struct i2c_driver {
> * calls it to pass on slave events to the slave driver.
> * @devres_group_id: id of the devres group that will be created for resources
> * acquired when probing this device.
> + * @turn_off_on_remove: Record if we have turned on the device before probing
> + * so we can turn off the device at removal.
> *
> * An i2c_client identifies a single device (i.e. chip) connected to an
> * i2c bus. The behaviour exposed to Linux is defined by the driver
> @@ -355,6 +357,8 @@ struct i2c_client {
> i2c_slave_cb_t slave_cb; /* callback for slave mode */
> #endif
> void *devres_group_id; /* ID of probe devres group */
> + bool turn_off_on_remove; /* if device needs to be turned */
> + /* off by framework at removal */
I don't know why the fields are documented twice. Someone wrote kerneldoc
documentation but forgot to remove the old comments? :-) Anyway, not a
fault of this patch, but these should probaly go.
> };
> #define to_i2c_client(d) container_of(d, struct i2c_client, dev)
>
>
--
Kind regards,
Sakari Ailus
