On Tue, 7 Mar 2023 10:10:50 -0500 Harry Wentland <harry.wentland@xxxxxxx> wrote: > This patchset is based on Joshua's previous patchset [1], as well > as my previous patchset [2]. > > It is > - enabling support for the colorspace property in amdgpu, as well as > - allowing drivers to specify the supported set of colorspaces, and > - deprecating the BT2020_YCC and BT2020_RGB properties in favor of > a common BT2020 property. We leave the BT2020_CYCC property untouched > for now, same as the other _YVV properties. If they'll see use later > we might need to do something similar there, or allow userspace to > decide on the output encoding (RGB vs YUV). > > Colorspace, Infoframes, and YCbCr matrix > --------------------------------------- > > Even though the initial intent of the colorspace property was to set the > colorspace field in the respective HDMI AVI and DP SDP infoframes that > is not sufficient in all scenarios. For DP the colorspace information > also affects the MSA (main stream attribute) packet. For YUV output the > colorspace affects the RGB-to-YCbCr conversion matrix. The colorspace > field of the infopackets also depends on the encoding used, which is > something that is decided by the driver and not known to userspace. > > For these reasons a driver will need to be able to select the supported > colorspaces at property creation. > > Note: There seems to be an understanding that the colorspace property > should ONLY modify the infoframe. While this is current behavior and > sufficient in some cases it is nowhere specified that this should be the > only use of this property. As outlined above this limitation is not > going to work in all cases. > > This patchset does not affect current behavior for the drivers that > implement this property: i915 and vc4. > > In the future we might want to give userspace control over the encoding > format on the wire, in particular to avoid use of YUV420 when image > fidelity is important. This work would likely go hand in hand with a > min_bpc property and wouldn't conflict with the work done in this > patchset. > > Colorspace on crtc or connector? > -------------------------------- > > There have been suggestions of programming 'colorspace' on the drm_crtc > but I don't think the crtc is the right place for this property. The > drm_plane and drm_crtc will be used to offload color processing that > would normally be done via the GFX or other pipelines. The drm_connector > controls the signalling with the display and ensures the wire format is > appropriate for the encoding by programming the RGB-to-YCbCr matrix. > > [1] https://patchwork.freedesktop.org/series/113632/ > [2] https://patchwork.freedesktop.org/series/111865/ Hi Harry, this is a really good cover letter. I've given all the comments I have on this iteration. Thanks, pq
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