On 22-08-19, Jacopo Mondi wrote: > Hi Marco > > On Fri, Aug 19, 2022 at 09:18:32AM +0200, Marco Felsch wrote: > > Hi Jacopo, > > > > thanks for your fast feedback :) > > > > On 22-08-18, Jacopo Mondi wrote: > > > Hi Marco > > > > > > On Thu, Aug 18, 2022 at 04:47:12PM +0200, Marco Felsch wrote: > > > > This is in preparation of switching to the generic dev PM mechanism. > > > > Since the .s_power callback will be removed in the near future move the > > > > powering into the .s_stream callback. So this driver no longer depends > > > > on the .s_power mechanism. > > > > > > > > Signed-off-by: Marco Felsch <m.felsch@xxxxxxxxxxxxxx> > > > > > > If you want to move to runtime_pm, I would implement it first and have > > > s_power call the _resume and _suspend routines, as some platform > > > drivers still use s_power() and some of them might depend on it. > > > > Do we really have platforms which depend on this? IMHO if that is the > > $ git grep "v4l2_subdev_call(.*, s_power" drivers/media/platform/ | cut -d : -f1 | uniq | wc -l > 8 > > > case than we should fix those platfoms. Since new drivers shouldn't use > > this callback anymore. > > Patches are clearly welcome I guess.. :) > > In my case, I worked on [1] and wondered why the sensor was enabled > > before I told him to do so. Since I didn't implement the s_power() > > callback, I had no chance to get enabled before. > > > > I'm not sure I got this part What I mean is, that the MT9M131 sensor gets enabled and immediately start sending frames before I told him to do so e.g. by calling s_stream(). This can confuse the downstream device. The only way to get enable the downstream device first is to add the s_power() callback. > > Can we please decide: > > - Do we wanna get rid of the s_power() callback? > > I think that would be everyone's desire, but drivers have to be moved > away from it > > > - If not, how do we handle those devices then with drivers not > > implementing this callback? > > By maintaining compatibility. I suggested to move to runtime_pm() and > wrap _resume/_suspend in s_power(). But then you're introducing new drivers with s_power() callbacks and so the behaviour isn't really changed. > My understanding is that the two (runtime_pm/s_power) are mutually > exclusive, but even if that was not the case, runtime_pm is reference > counted, hence as long as calls are balanced this should work, right ? Right but the s_power() behaviour is not changed and drivers still rely on it to work as right now. Regards, Marco
