On Thu, Mar 16, 2023 at 01:34:49PM +0200, Pekka Paalanen wrote: > On Thu, 16 Mar 2023 12:47:51 +0200 > Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> wrote: > > > On Thu, Mar 16, 2023 at 12:07:01PM +0200, Pekka Paalanen wrote: > > > On Thu, 16 Mar 2023 11:50:27 +0200 > > > Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> wrote: > > > > > > > On Thu, Mar 16, 2023 at 01:37:24AM +0100, Sebastian Wick wrote: > > > > > On Tue, Mar 7, 2023 at 4:12 PM Harry Wentland <harry.wentland@xxxxxxx> wrote: > > > > > > > > > > > > We want compositors to be able to set the output > > > > > > colorspace on DP and HDMI outputs, based on the > > > > > > caps reported from the receiver via EDID. > > > > > > > > > > About that... The documentation says that user space has to check the > > > > > EDID for what the sink actually supports. So whatever is in > > > > > supported_colorspaces is just what the driver/hardware is able to set > > > > > but doesn't actually indicate that the sink supports it. > > > > > > > > > > So the only way to enable bt2020 is by checking if the sink supports > > > > > both RGB and YUV variants because both could be used by the driver. > > > > > Not great at all. Something to remember for the new property. > > > > > > > > Hmm. I wonder if that's even legal... Looks like maybe it > > > > is since I can't immediately spot anything in CTA-861 to > > > > forbid it :/ > > > > > > Wouldn't the driver do the same EDID check before choosing whether it > > > uses RGB or YCbCr signalling? > > > > I suppose it could. The modeset would then fail, which is perhaps > > Could? What are they missing? The fact that the new property that also affects the rgb->ycbcr matrix doesn't even exist? > > I mean, drivers are already automatically choosing between RGB and YCbCr > signalling based on e.g. available bandwidth. Surely they already will > not attempt to send a signal format to a monitor that does not say it > supports that? We just signal default/bt.709 colorimetry. There is nothing to check for those IIRC. > > > not a huge issue, except maybe for suspend+resume if we fail in > > the resume path. Although I guess the EDID/etc. should not yet > > be refreshed at that point so if the modeset worked before suspend > > resume should be able to restore it without failures. > > I assumed that if a monitor can be driven, and it supports any BT2020 > format, then it always supports the BT2020 format it is being driven > in (RGB vs. YCbCr flavors). Bad assumption? I didn't spot any rule that both must be there. But didn't look too hard either. -- Ville Syrjälä Intel
