On Mon 24 May 02:30 CDT 2021, Vinod Koul wrote: > On 21-05-21, 09:42, Bjorn Andersson wrote: > > On Fri 21 May 07:49 CDT 2021, Vinod Koul wrote: > > > > > DSC enables streams to be compressed before we send to panel. This > > > requires DSC enabled encoder and a panel to be present. So we add this > > > information in board DTS and find if DSC can be enabled and the > > > parameters required to configure DSC are added to binding document along > > > with example > > > > > > Signed-off-by: Vinod Koul <vkoul@xxxxxxxxxx> > > > --- > > > .../devicetree/bindings/display/msm/dsi.txt | 15 +++++++++++++++ > > > 1 file changed, 15 insertions(+) > > > > > > diff --git a/Documentation/devicetree/bindings/display/msm/dsi.txt b/Documentation/devicetree/bindings/display/msm/dsi.txt > > > index b9a64d3ff184..83d2fb92267e 100644 > > > --- a/Documentation/devicetree/bindings/display/msm/dsi.txt > > > +++ b/Documentation/devicetree/bindings/display/msm/dsi.txt > > > @@ -48,6 +48,13 @@ Optional properties: > > > - pinctrl-n: the "sleep" pinctrl state > > > - ports: contains DSI controller input and output ports as children, each > > > containing one endpoint subnode. > > > +- qcom,mdss-dsc-enabled: Display Stream Compression (DSC) is enabled > > > +- qcom,mdss-slice-height: DSC slice height in pixels > > > +- qcom,mdss-slice-width: DSC slice width in pixels > > > +- qcom,mdss-slice-per-pkt: DSC slices per packet > > > +- qcom,mdss-bit-per-component: DSC bits per component > > > +- qcom,mdss-bit-per-pixel: DSC bits per pixel > > > +- qcom,mdss-block-prediction-enable: Block prediction mode of DSC enabled > > > > > > DSI Endpoint properties: > > > - remote-endpoint: For port@0, set to phandle of the connected panel/bridge's > > > @@ -188,6 +195,14 @@ Example: > > > qcom,master-dsi; > > > qcom,sync-dual-dsi; > > > > > > + qcom,mdss-dsc-enabled; > > > > To me the activation of DSC seems to be a property of the panel. > > I think there are three parts to the problem > 1. Panel needs to support it In the case of DP there's bits to be read in the panel to figure this out, for DSI panels this seems like a property that the panel (driver) should know about. > 2. Host needs to support it Right, so this needs to be known by the driver. My suggestion is that we derive it from the compatible or from the HW version. > 3. Someone needs to decide to use when both the above conditions are > met. > > There are cases where above 1, 2 will be satisfied, but we might be okay > without DSC too.. so how to decide when to do DSC :) > Can we describe those cases? E.g. is it because enabling DSC would not cause a reduction in clock speed that's worth the effort? Or do we only use DSC for DSI when it allows us to squeeze everything into a single link? Regards, Bjorn > I feel it is more of a system property. And I also think that these > parameters here are host configuration and not really for panel... > > > > > > + qcom,mdss-slice-height = <16>; > > > + qcom,mdss-slice-width = <540>; > > > + qcom,mdss-slice-per-pkt = <1>; > > > + qcom,mdss-bit-per-component = <8>; > > > + qcom,mdss-bit-per-pixel = <8>; > > > + qcom,mdss-block-prediction-enable; > > > > Which of these properties relates to the DSC encoder and what needs to > > be agreed with the sink? Can't we derive e.g. bpp from the information > > we have from the attached panel already? > > Let me go back and check on this a bit more > > Thanks > -- > ~Vinod
