[PATCH] drm/i915/display: Workaround for odd panning for planar yuv

[Garg, Nemesa]

> -----Original Message-----
> From: Kandpal, Suraj <suraj.kandpal at intel.com>
> Sent: Tuesday, October 15, 2024 2:33 PM
> To: Garg, Nemesa <nemesa.garg at intel.com>; intel-gfx at lists.freedesktop.org
> Cc: Garg, Nemesa <nemesa.garg at intel.com>
> Subject: RE: [PATCH] drm/i915/display: Workaround for odd panning for planar
> yuv
> 
> 
> 
> > -----Original Message-----
> > From: Intel-gfx <intel-gfx-bounces at lists.freedesktop.org> On Behalf Of
> > Nemesa Garg
> > Sent: Monday, September 30, 2024 4:54 PM
> > To: intel-gfx at lists.freedesktop.org
> > Cc: Garg, Nemesa <nemesa.garg at intel.com>
> > Subject: [PATCH] drm/i915/display: Workaround for odd panning for
> > planar yuv
> >
> > Disable the support for odd x pan for even xsize for NV12 format as
> > underrun issue is seen.
> >
> > WA: 16024459452
> >
> > v2: Replace HSD with WA in commit message [Suraj]
> >     Modified the condition for handling odd panning
> >
> > v3: Simplified the condition for checking hsub
> >     Using older framework for wa as rev1[Jani]
> >
> > v4: Modify the condition for hsub [Sai Teja]
> >     Initialize hsub in else path [Dan]
> >
> > v5: Replace IS_LUNARLAKE with display version.
> >     Resolve nitpicks[Jani]
> >
> > Signed-off-by: Nemesa Garg <nemesa.garg at intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_atomic_plane.c | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_atomic_plane.c
> > b/drivers/gpu/drm/i915/display/intel_atomic_plane.c
> > index e979786aa5cf..e3401a4f7992 100644
> > --- a/drivers/gpu/drm/i915/display/intel_atomic_plane.c
> > +++ b/drivers/gpu/drm/i915/display/intel_atomic_plane.c
> > @@ -1029,6 +1029,14 @@ int intel_plane_check_src_coordinates(struct
> > intel_plane_state *plane_state)
> >  		 * This allows NV12 and P0xx formats to have odd size and/or
> odd
> >  		 * source coordinates on DISPLAY_VER(i915) >= 20
> >  		 */
> > +		/*
> > +		 *  Wa_16023981245 for display version 20.
> > +		 *  Do not support odd x-panning for even xsize for NV12.
> 
> Only mention WA no here the rest anyone can refer to by going and checking the
> HSD
Sure..will do.
> 
> > +		 */
> > +		if (DISPLAY_VER(i915) == 20 && fb->format->format ==
> > DRM_FORMAT_NV12 &&
> > +		    src_x % 2 != 0 && src_w % 2 == 0)
> > +			return -EINVAL;
> 
> Also rather than return -EINVAL here we set hsub =2 and vsub =1 this should
> make sure odd panning is disabled When we have even size since we only need to
> disable odd panning according to hsd not even panning this return may end stop
> panning for even sizes all together.
> 
Even if I do hsub=2 then also it will return -EINVAL as src_x will be odd and src_x % hsub will be 1 which will return -EINVAL.
Even panning doesn't get disable that's why I have added the check src_x % 2 != 0 to make sure that position in not even
and src_w % 2 to check for even size.

Regards,
Nemesa

> Regards,
> Suraj Kandpal
> > +
> >  		hsub = 1;
> >  		vsub = 1;
> >  	} else {
> > --
> > 2.25.1