[igt-dev] [PATCH i-g-t] [i-g-t] tests/kms_plane_scaling: fb height to be multiplier of 4 for YUV 420 planar

[Srinivas, Vidya]

> -----Original Message-----
> From: Ville Syrjälä [mailto:ville.syrjala at linux.intel.com]
> Sent: Friday, March 16, 2018 8:01 PM
> To: Srinivas, Vidya <vidya.srinivas at intel.com>
> Cc: igt-dev at lists.freedesktop.org; Kamath, Sunil <sunil.kamath at intel.com>;
> Syrjala, Ville <ville.syrjala at intel.com>
> Subject: Re: [igt-dev] [PATCH i-g-t] [i-g-t] tests/kms_plane_scaling: fb height
> to be multiplier of 4 for YUV 420 planar
> 
> On Fri, Mar 16, 2018 at 06:50:27PM +0530, Vidya Srinivas wrote:
> > For Gen9, GLK, CNL, GLV: Display WA 1106:
> > Display corruption/color shift observed when using NV12 with
> > 270 rotation or 90 rotation + horizontal flip.
> > WA: NV12 with 270 rotation or 90 rotation + horizontal flip requires
> > the programmed plane height to be a multiple of 4.
> > Patch changes the NV12 buffer to 20x20 to maintain both fb > min fb
> > and also multiplier of 4
> >
> > Signed-off-by: Uma Shankar <uma.shankar at intel.com>
> > Signed-off-by: Vidya Srinivas <vidya.srinivas at intel.com>
> > ---
> >  tests/kms_plane_scaling.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/tests/kms_plane_scaling.c b/tests/kms_plane_scaling.c
> > index 36fcfc0..b94d785 100644
> > --- a/tests/kms_plane_scaling.c
> > +++ b/tests/kms_plane_scaling.c
> > @@ -132,7 +132,7 @@ static void check_scaling_pipe_plane_rot(data_t *d,
> igt_plane_t *plane,
> >  	/* create buffer in the range of  min and max source side limit.*/
> >  	width = height = 9;
> >  	if (pixel_format == DRM_FORMAT_NV12)
> > -		width = height = 17;
> > +		width = height = 20;
> 
> Why 20 and not 16? I thought 16 was the limit?

Yes, but when the NV12 17x17 buffer is flipped on the sprite, it gets adjusted to 16x16 in
Intel_check_sprite_plane and further PLANE_SIZE gets written with 15x15.

So, I thought 20x20 would be better. However when I run the kms_plane_scaling with rotation
About 100 times, I still see rare fifo underruns. This may be due to the WA1106
Which says the plane height for NV12 in case of rotation needs to be multiplier of 4.
Even with 20x20 buffer, after the adjustment it changes to 18x19 and this further reduces to 17x18 in skl_update_plane
This causes 18 to be programmed as plane height which is not a multiplier of 4.

So this patch too is not good :( Sorry about pushing this.

Regards
Vidya

> 
> >  	igt_create_color_fb(display->drm_fd, width, height,
> >  		       pixel_format, tiling, 0.0, 1.0, 0.0, &d->fb[0]);
> >  	igt_plane_set_fb(plane, &d->fb[0]);
> > --
> > 2.7.4
> >
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> > igt-dev at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/igt-dev
> 
> --
> Ville Syrjälä
> Intel OTC