[PATCH] radeon: insert 10ms sleep in dce5_crtc_load_lut

[Alex Deucher]

On Tue, Jan 28, 2020 at 4:21 PM Alex Deucher <alexdeucher at gmail.com> wrote:
>
> On Tue, Jan 28, 2020 at 11:10 AM Daniel Vetter <daniel.vetter at ffwll.ch> wrote:
> >
> > Per at least one tester this is enough magic to recover the regression
> > introduced for some people (but not all) in
> >
> > commit b8e2b0199cc377617dc238f5106352c06dcd3fa2
> > Author: Peter Rosin <peda at axentia.se>
> > Date:   Tue Jul 4 12:36:57 2017 +0200
> >
> >     drm/fb-helper: factor out pseudo-palette
> >
> > which for radeon had the side-effect of refactoring out a seemingly
> > redudant writing of the color palette.
> >
> > 10ms in a fairly slow modeset path feels like an acceptable form of
> > duct-tape, so maybe worth a shot and see what sticks.
> >
> > Cc: Alex Deucher <alexander.deucher at amd.com>
> > Cc: Michel Dänzer <michel.daenzer at amd.com>
> > References: https://bugzilla.kernel.org/show_bug.cgi?id=198123
> > Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
>
> Works for me.  Applied.  Thanks!

Actually, thinking about this more, I wonder if this will have adverse
affects on stuff that messes with the LUT like various fade effects in
compositors.  I guess we can cross that bridge when we get to it.

Alex


>
> Alex
>
>
> > ---
> >  drivers/gpu/drm/radeon/radeon_display.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
> > index 354756e00fe1..d07c7db0c815 100644
> > --- a/drivers/gpu/drm/radeon/radeon_display.c
> > +++ b/drivers/gpu/drm/radeon/radeon_display.c
> > @@ -127,6 +127,8 @@ static void dce5_crtc_load_lut(struct drm_crtc *crtc)
> >
> >         DRM_DEBUG_KMS("%d\n", radeon_crtc->crtc_id);
> >
> > +       msleep(10);
> > +
> >         WREG32(NI_INPUT_CSC_CONTROL + radeon_crtc->crtc_offset,
> >                (NI_INPUT_CSC_GRPH_MODE(NI_INPUT_CSC_BYPASS) |
> >                 NI_INPUT_CSC_OVL_MODE(NI_INPUT_CSC_BYPASS)));
> > --
> > 2.24.1
> >
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