[PATCH] drm/amd/display: Try YCbCr420 color when YCbCr444 fails

[Alex Deucher]

Applied.  Thanks!

Alex

On Fri, Mar 26, 2021 at 10:59 AM Harry Wentland <harry.wentland at amd.com> wrote:
>
>
>
> On 2021-03-24 4:23 p.m., Alex Deucher wrote:
> > On Wed, Mar 17, 2021 at 11:25 AM Werner Sembach <wse at tuxedocomputers.com> wrote:
> >>
> >> When encoder validation of a display mode fails, retry with less bandwidth
> >> heavy YCbCr420 color mode, if available. This enables some HDMI 1.4 setups
> >> to support 4k60Hz output, which previously failed silently.
> >>
> >> On some setups, while the monitor and the gpu support display modes with
> >> pixel clocks of up to 600MHz, the link encoder might not. This prevents
> >> YCbCr444 and RGB encoding for 4k60Hz, but YCbCr420 encoding might still be
> >> possible. However, which color mode is used is decided before the link
> >> encoder capabilities are checked. This patch fixes the problem by retrying
> >> to find a display mode with YCbCr420 enforced and using it, if it is
> >> valid.
> >>
> >> Signed-off-by: Werner Sembach <wse at tuxedocomputers.com>
> >> Cc: <stable at vger.kernel.org>
> >
> >
> > This seems reasonable to me.  Harry, Leo, Any objections?
> >
>
> Looks good to me.
>
> Reviewed-by: Harry Wentland <harry.wentland at amd.com>
>
> Harry
>
> > Alex
> >
> >> ---
> >>
> >>  From c9398160caf4ff20e63b8ba3a4366d6ef95c4ac3 Mon Sep 17 00:00:00 2001
> >> From: Werner Sembach <wse at tuxedocomputers.com>
> >> Date: Wed, 17 Mar 2021 12:52:22 +0100
> >> Subject: [PATCH] Retry forcing YCbCr420 color on failed encoder validation
> >>
> >> ---
> >>   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 9 +++++++++
> >>   1 file changed, 9 insertions(+)
> >>
> >> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> >> index 961abf1cf040..2d16389b5f1e 100644
> >> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> >> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> >> @@ -5727,6 +5727,15 @@ create_validate_stream_for_sink(struct amdgpu_dm_connector *aconnector,
> >>
> >>          } while (stream == NULL && requested_bpc >= 6);
> >>
> >> +       if (dc_result == DC_FAIL_ENC_VALIDATE && !aconnector->force_yuv420_output) {
> >> +               DRM_DEBUG_KMS("Retry forcing YCbCr420 encoding\n");
> >> +
> >> +               aconnector->force_yuv420_output = true;
> >> +               stream = create_validate_stream_for_sink(aconnector, drm_mode,
> >> +                                               dm_state, old_stream);
> >> +               aconnector->force_yuv420_output = false;
> >> +       }
> >> +
> >>          return stream;
> >>   }
> >>
> >> --
> >> 2.25.1
> >>
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