[Intel-gfx] [PATCH v2] drm/i915: correct the pitch check for NV12 framebuffer

[Hwang, Dongseong]

On Wed, Dec 12, 2018 at 1:15 PM Ville Syrjälä
<ville.syrjala at linux.intel.com> wrote:
>
> On Wed, Dec 12, 2018 at 09:33:49PM +0100, Daniel Vetter wrote:
> > On Wed, Dec 12, 2018 at 9:24 PM Ville Syrjälä
> > <ville.syrjala at linux.intel.com> wrote:
> > >
> > > On Tue, Dec 11, 2018 at 04:39:05PM -0800, Dongseong Hwang wrote:
> > > > framebuffer for NV12 requires the pitch to the multiplier of 4, instead
> > > > of the width. This patch corrects it.
> > > >
> > > > For instance, a 480p video, whose width and pitch are 854 and 896
> > > > respectively, is excluded for NV12 plane so far.
> > > >
> > > > Signed-off-by: Dongseong Hwang <dongseong.hwang at intel.com>
> > > > Cc: Chandra Konduru <chandra.konduru at intel.com>
> > > > Cc: Vidya Srinivas <vidya.srinivas at intel.com>
> > > > Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > > > Cc: Juha-Pekka Heikkila <juhapekka.heikkila at gmail.com>
> > > > ---
> > > >  drivers/gpu/drm/i915/intel_display.c | 2 +-
> > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > > > index 13e5650..8a3de12 100644
> > > > --- a/drivers/gpu/drm/i915/intel_display.c
> > > > +++ b/drivers/gpu/drm/i915/intel_display.c
> > > > @@ -14600,7 +14600,7 @@ static int intel_framebuffer_init(struct intel_framebuffer *intel_fb,
> > > >       if (fb->format->format == DRM_FORMAT_NV12 &&
> > > >           (fb->width < SKL_MIN_YUV_420_SRC_W ||
> > > >            fb->height < SKL_MIN_YUV_420_SRC_H ||
> > > > -          (fb->width % 4) != 0 || (fb->height % 4) != 0)) {
> > > > +          (fb->pitches[0] % 4) != 0 || (fb->height % 4) != 0)) {
> > >
> > > The stride can never be misaligned like that. It'll be at least tile
> > > aligned, or 64 byte aligned with linear buffers.
> > >
> > > Anyways this entire piece of code doesn't make too much sense. The fb
> > > size doesn't really matter for us, only the src viewport size matters.
> > > That one we limit to a minimum of 2x2 pixels w/o scaling, and 16x16
> > > pixems w/ scaling. So looks like this code can be just ripped out.
> >
> > Do we have igt testcases for these cornercases in igt? Obviously would
> > need to be intel specific subtests ...
>
> Can't spot anything quite that specific. Someone would need to write
> one I suppose. Also Imre has a test somewhere on the list for testing
> the plane clipping underrun fails which tests small src viewport sizes,
> and JP has been working on a rotation vs. clipping test that is also
> somewhat related. Not sure if we could combine any of these somehow
> to avoid having too many similar tests.

Ap pointed out there is i915 workaround

1106 Display NV12, Rotation, Horizontal flip
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.
GEN9:ALL
GLK:ALL
GLV:ALL
CNL:*:A
CNL:*:B

I think this condition was introduced to deal with the workaround, and
I think the stride restriction is enough for the above workaround.
Ville, if I add the igt covering this change, is it good to land?

Best regards,
Dongseong


>
> --
> Ville Syrjälä
> Intel