Re: [PATCH] media: dw9768: activate runtime PM and turn off device

[Bingbu Cao <bingbu.cao@linux.intel.com>]

On 11/5/21 2:54 PM, Tomasz Figa wrote:
> On Fri, Oct 15, 2021 at 3:12 PM Bingbu Cao <bingbu.cao@intel.com> wrote:
>>
>> When dw9768 working with ACPI systems, the dw9768 was turned
>> by i2c-core during probe, driver need activate the PM runtime
>> and ask runtime PM to turn off the device.
>>
>> Signed-off-by: Bingbu Cao <bingbu.cao@intel.com>
>> ---
>>  drivers/media/i2c/dw9768.c | 6 ++++++
>>  1 file changed, 6 insertions(+)
>>
>> diff --git a/drivers/media/i2c/dw9768.c b/drivers/media/i2c/dw9768.c
>> index c086580efac7..65c6acf3ced9 100644
>> --- a/drivers/media/i2c/dw9768.c
>> +++ b/drivers/media/i2c/dw9768.c
>> @@ -469,6 +469,11 @@ static int dw9768_probe(struct i2c_client *client)
>>
>>         dw9768->sd.entity.function = MEDIA_ENT_F_LENS;
>>
>> +       /*
>> +        * Device is already turned on by i2c-core with ACPI domain PM.
>> +        * Attempt to turn off the device to satisfy the privacy LED concerns.
>> +        */
>> +       pm_runtime_set_active(dev);
> 
> This driver is used by non-ACPI systems as well. This change will make
> the PM core not call the runtime_resume() callback provided by the
> driver and the power would never be turned on on such systems.

Tomasz,

Why the runtime_set_active() and runtime_idle() break the runtime
PM on non-ACPI systems? Did it cause the PM runtime enable failure or
incorrect PM usage count?

> 
> Wasn't the intention of Sakari's ACPI patches to allow bypassing the
> ACPI domain power on at boot up and eliminate the need for this
> change?
> 
> Best regards,
> Tomasz
> 
>>
>>         pm_runtime_enable(dev);
>>         if (!pm_runtime_enabled(dev)) {
>>                 ret = dw9768_runtime_resume(dev);
>> @@ -483,6 +488,7 @@ static int dw9768_probe(struct i2c_client *client)
>>                 dev_err(dev, "failed to register V4L2 subdev: %d", ret);
>>                 goto err_power_off;
>>         }
>> +       pm_runtime_idle(dev);
>>
>>         return 0;
>>
>> --
>> 2.7.4
>>

-- 
Best regards,
Bingbu Cao