[PATCH] [media] pxa_camera: fix module remove codepath for v4l2 clock

[petr.cvek@tul.cz (Petr Cvek)]

Dne 27.4.2017 v 21:20 Robert Jarzmik napsal(a):
> Petr Cvek <petr.cvek@tul.cz> writes:
> 
>> The conversion from soc_camera omitted a correct handling of the clock
>> gating for a sensor. When the pxa_camera driver module was removed it
>> tried to unregister clk, but this caused a similar warning:
>>
>>   WARNING: CPU: 0 PID: 6740 at drivers/media/v4l2-core/v4l2-clk.c:278
>>   v4l2_clk_unregister(): Refusing to unregister ref-counted 0-0030 clock!
>>
>> The clock was at time still refcounted by the sensor driver. Before
>> the removing of the pxa_camera the clock must be dropped by the sensor
>> driver. This should be triggered by v4l2_async_notifier_unregister() call
>> which removes sensor driver module too, calls unbind() function and then
>> tries to probe sensor driver again. Inside unbind() we can safely
>> unregister the v4l2 clock as the sensor driver got removed. The original
>> v4l2_clk_unregister() should be put inside test as the clock can be
>> already unregistered from unbind(). If there was not any bound sensor
>> the clock is still present.
>>
>> The codepath is practically a copy from the old soc_camera. The bug was
>> tested with a pxa_camera+ov9640 combination during the conversion
>> of the ov9640 from the soc_camera.
>>
>> Signed-off-by: Petr Cvek <petr.cvek@tul.cz>
> 
> Yeah, it's way better with this patch, especially the insmod/rmmod/insmod/rmmod
> test.

I will post some other bugfixes (and feature adding) for pxa_camera soon. Do you wish to be CC'd? 

P.S. Who is the the maintainer of pxa_camera BTW? Still Guennadi Liakhovetski? Basically pxa_camera is no longer part of the soc_camera and MAINTAINERS file does not exactly specify pxa_camera.c (I'm asking because I will send the patch for ov9640 soc_camera removal too :-D).

Best regards,
Petr