On 06/29/18 12:06, Mauro Carvalho Chehab wrote: > Em Thu, 28 Jun 2018 14:47:05 +0200 > Hans Verkuil <hverkuil@xxxxxxxxx> escreveu: > >> On 06/28/18 13:37, Mauro Carvalho Chehab wrote: >>> Em Thu, 17 May 2018 16:30:16 +0200 >>> Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx> escreveu: >>> >>>> There is no way to control the standard of subdevices which are part of >>>> a media device. The ioctls which exists all target video devices >>>> explicitly and the idea is that the video device should talk to the >>>> subdevice. For subdevices part of a media graph this is not possible and >>>> the standard must be controlled on the subdev device directly. >>> >>> Why isn't it possible? A media pipeline should have at least a video >>> devnode where the standard ioctls will be issued. >> >> Not for an MC-centric device like the r-car or imx. It's why we have v4l-subdev >> ioctls for the DV_TIMINGS API, but the corresponding SDTV standards API is >> missing. >> >> And in a complex scenario there is nothing preventing you from having multiple >> SDTV inputs, some of which need PAL-BG, some SECAM, some NTSC (less likely) >> which are all composed together (think security cameras or something like that). >> >> You definitely cannot set the standard from a video device. If nothing else, >> it would be completely inconsistent with how HDMI inputs work. >> >> The whole point of MC centric devices is that you *don't* control subdevs >> from video nodes. > > Well, the way it is, this change is disruptive, as, as far as I remember, > MC-based devices with tvp5150 already sets STD via the /dev/video device. Really? Which driver? I am not aware of this and I think you are mistaken. Remember that we are talking about MC-centric drivers. em28xx is not MC-centric, even though it has a media device. > > If we're willing to add it, we'll need to be clear when one approach > should be taken, and be clear that, if the SUBDEV version is used, the > driver should not support the non-subdev option. Of course, but in the case of em28xx the tvp5150 v4l-subdev node is never created, so this is not a problem. Regards, Hans > >> >> Regards, >> >> Hans >> >>> So, I don't see why you would need to explicitly set the standard inside >>> a sub-device. >>> >>> The way I see, inside a given pipeline, all subdevs should be using the >>> same video standard (maybe except for a m2m device with would have some >>> coded that would be doing format conversion). >>> >>> Am I missing something? >>> >>> Thanks, >>> Mauro >>> >> > > > > Thanks, > Mauro >
