Hi Ville, On 04-01-2017 16:36, Ville Syrjälä wrote: > On Wed, Jan 04, 2017 at 04:15:01PM +0000, Jose Abreu wrote: >> [snip] >>> Why does userspace need to know this? My thinking has been that the >>> driver would do the right thing automagically. >>> >>> We do probably want some kind of output colorspace property to allow the >>> user to select between RGB vs. YCbCr etc. But I think even with that we >>> should still allow the driver to automagically select YCbCr 4:2:0 output >>> since that's the only way the mode will work. >> I agree. When only 4:2:0 is supported there is no need to expose >> the flag to userspace. How shall then I signal drivers for this >> 4:2:0'only sampling mode? >> >> So, for the remaining modes, you propose a new field in the mode >> structure called 'colorspace' which contains the list of >> supported sampling modes for the given mode? I think it would be >> a nice addition. This way if a mode supports only RGB we only >> passed RGB flag; if 4:2:0 was also supported we passed the 4:2:0 >> flag, ... And then user could select. We also have to inform user >> which one is being actually used. > IIRC there aren't any "RGB only" modes or anything like that. So > YCbCr 4:2:0 is the special case here. We could just add something to the > mode struct for it, or do we already have some other flags thing that's > not exposed to userspace? And I guess drivers should be able to opt into > supporting these 4:2:0 modes in similar way they opt into > interlaced/stereo/whatever. I mean, if a source EDID does not declare support for YCbCr modes (4:2:2 and 4:4:4 [i think they have to be both supported if sink supports != RGB]) then only RGB can be used. Or is any YCbCr that is pre-required? Still, I see your point. When EDID declares support for YCbCr then all modes can use it, and not only some of them. I think for stereo modes the flags can be opt in/out in userspace exposing. There is a function called drm_mode_expose_to_userspace() which only exposes stereo modes if user asks to. We could do something similar for 4:2:0 modes (or even for all pixel encoding). i.e. expose which encoding can be used in current video mode. What do you think? About drivers opting in for 4:2:0 modes, then you propose a new field in drm_connector (called for example ycbcr_420_allowed) which only does the parsing of the 4:2:0 modes and adds them to the list when set to true? Best regards, Jose Miguel Abreu > >> Best regards, >> Jose Miguel Abreu >> >>> [snip] _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
