On Mon, Sep 23, 2019 at 12:16:12PM +0000, Brian Starkey wrote: > Hi Lowry, > > On Fri, Sep 20, 2019 at 09:43:47AM +0000, Lowry Li (Arm Technology China) wrote: > > From: "Lowry Li (Arm Technology China)" <Lowry.Li@xxxxxxx> > > > > Sets color_depth according to connector->bpc. > > Adds a new optional DT attribute "color-format" to represent a > > preferred color formats for a specific pipeline, and the select order > > is: > > YCRCB420 > YCRCB422 > YCRCB444 > RGB444 > > The color-format can be anyone of these 4 format, one color-format not > > only represent one format, but also include the lower formats, like > > > > color-format preferred_color_formats > > YCRCB420 YCRCB420 > YCRCB422 > YCRCB444 > RGB444 > > YCRCB422 YCRCB422 > YCRCB444 > RGB444 > > YCRCB444 YCRCB444 > RGB444 > > RGB444 RGB444 > > > > Then the final color_format is calculated by 3 steps: > > 1. calculate HW available formats. > > avail_formats = connector_color_formats & improc->color_formats; > > 2. filter out un-preferred format. > > avail_formats &= preferred_color_formats; > > 3. select the final format according to the preferred order. > > color_format = BIT(__fls(aval_formats)); > > Is there a specific use-case for the DT property for selecting color > format? > > I think in general the color format should be determined according to > the rules in the CEA spec. There's also the drm_mode_is_420_only() > helper we can use to determine if YCBCR420 must be used. For the cases > where it's optional, I think we can default to RGB444. That is the policy we have in i915. We have a vague plan to add a new property for the user to select the encoding explicitly (which would also allow things like YCbCr 4:4:4), but IIRC no one has actually sent a patch for that. CTA-861 sort of seems to say that one should favor YCbCr over RGB iff both sides support it, but I think RGB is probably the better default because it means straight passthrough (minus the annoying full->limit quantization range trickery). -- Ville Syrjälä Intel _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
