On 26-05-21, 09:00, Jeffrey Hugo wrote: > On Tue, May 25, 2021 at 11:46 PM Vinod Koul <vkoul@xxxxxxxxxx> wrote: > > On 21-05-21, 08:09, Jeffrey Hugo wrote: > > > On Fri, May 21, 2021 at 6:50 AM Vinod Koul <vkoul@xxxxxxxxxx> wrote: > > > > > > > > Display Stream Compression (DSC) compresses the display stream in host which > > > > is later decoded by panel. This series enables this for Qualcomm msm driver. > > > > This was tested on Google Pixel3 phone which use LGE SW43408 panel. > > > > > > > > The changes include adding DT properties for DSC then hardware blocks support > > > > required in DPU1 driver and support in encoder. We also add support in DSI > > > > and introduce required topology changes. > > > > > > > > In order for panel to set the DSC parameters we add dsc in drm_panel and set > > > > it from the msm driver. > > > > > > > > Complete changes which enable this for Pixel3 along with panel driver (not > > > > part of this series) and DT changes can be found at: > > > > git.linaro.org/people/vinod.koul/kernel.git pixel/dsc_rfc > > > > > > > > Comments welcome! > > > > > > This feels backwards to me. I've only skimmed this series, and the DT > > > changes didn't come through for me, so perhaps I have an incomplete > > > view. > > > > Not sure why, I see it on lore: > > https://lore.kernel.org/dri-devel/20210521124946.3617862-3-vkoul@xxxxxxxxxx/ > > > > > DSC is not MSM specific. There is a standard for it. Yet it looks > > > like everything is implemented in a MSM specific way, and then pushed > > > to the panel. So, every vendor needs to implement their vendor > > > specific way to get the DSC info, and then push it to the panel? > > > Seems wrong, given there is an actual standard for this feature. > > > > I have added slice and bpp info in the DT here under the host and then > > pass the generic struct drm_dsc_config to panel which allows panel to > > write the pps cmd > > > > Nothing above is MSM specific.. It can very well work with non MSM > > controllers too. > > I disagree. > > The DT bindings you defined (thanks for the direct link) are MSM > specific. I'm not talking (yet) about the properties you defined, but > purely from the stand point that you defined the binding within the > scope of the MSM dsi binding. No other vendor can use those bindings. > Of course, if we look at the properties themselves, they are prefixed > with "qcom", which is vendor specific. > > So, purely on the face of it, this is MSM specific. > > Assuming we want a DT solution for DSC, I think it should be something > like Documentation/devicetree/bindings/clock/clock-bindings.txt (the > first example that comes to mind), which is a non-vendor specific > generic set of properties that each vendor/device specific binding can > inherit. Panel has similar things. > > Specific to the properties, I don't much like that you duplicate BPP, > which is already associated with the panel (although perhaps not in > the scope of DT). What if the panel and your DSC bindings disagree? > Also, I guess I need to ask, have you read the DSC spec? Last I > looked, there were something like 3 dozen properties that could be > configured. You have five in your proposed binding. To me, this is > not a generic DSC solution, this is MSM specific (and frankly I don't > think this supports all the configuration the MSM hardware can do, > either). I would concede the point that DT is msm specific. I dont disagree on making them a common dsc biding which anyone can use. I think your idea does have merits... I am still not sure who should include these properties, would it be the panel or host. Either would work and rest of the system can use these properties... -- ~Vinod
