Re: [PATCH] Fix suspend/resume of pxa_camera driver

[Robert Jarzmik <robert.jarzmik@free.fr>]

Guennadi Liakhovetski <g.liakhovetski@gmx.de> writes:

>> >> For the camera part, by now, I'm using standard suspend/resume functions of the
>> >> platform driver (mt9m111.c). It does work, but it's not clean ATM. The chaining
>> >> between the driver resume function and the availability of the I2C bus are not
>> >> properly chained. I'm still working on it.
>> >
>> > Yes, we have to clarify this too.
All right, I have my mind clarified, let's discuss now.

>>  - I cook up a clean suspend/resume (unless you did it first of course :)
Well, let's expose what we're facing here :
 - our video chip driver (ex: mt9m111) is an i2c driver
  => its resume function is called when i2c bus is resumed, so all is fine here

 - our video chip needs an external clock to work
  => example: mt9m111 needs a clock from pxa camera interface to have its i2c
  unit enabled
  => the mt9m111 driver resume function is unusable, as pxa_camera is resumed
  _after_ mt9m111, and thus mt9m111's i2c unit is not available at that moment

 - a working suspend/resume restores fully the video chip state
  => restores width/height/bpp
  => restores autoexposure, brightness, etc ...
  => all that insures userland is not impacted by suspend/resume

So, the only way I see to have suspend/resume working is :
 - modify soc_camera_ops to add suspend and resume functions
 - add suspend and resume functions in each chip driver (mt9m001, mt9m111, ...)
 - modify soc_camera.c (or pxa_camera.c ?) to call icd->ops->suspend() and
 icd->ops->resume()
 - modify pxa_camera.c (the patch I sent before)

Would you find that acceptable, or is there a better way ?

--
Robert

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