[Mesa-dev] [PATCH] anv/device: Add limits for InterpolationOffset

[Anuj Phogat]

On Thu, Jul 28, 2016 at 6:31 PM, Jason Ekstrand <jason at jlekstrand.net>
wrote:

> On Jul 28, 2016 7:37 PM, "Anuj Phogat" <anuj.phogat at gmail.com> wrote:
> >
> > Fixes the vulkan cts regression in test
> dEQP-VK.api.info.device.properties
> >
> > Cc: Mark Janes <mark.a.janes at intel.com>
> > Cc: Jason Ekstrand <jason at jlekstrand.net>
> > Signed-off-by: Anuj Phogat <anuj.phogat at gmail.com>
> > ---
> >  src/intel/vulkan/anv_device.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/src/intel/vulkan/anv_device.c
> b/src/intel/vulkan/anv_device.c
> > index c2c5153..9fd9683 100644
> > --- a/src/intel/vulkan/anv_device.c
> > +++ b/src/intel/vulkan/anv_device.c
> > @@ -524,9 +524,9 @@ void anv_GetPhysicalDeviceProperties(
> >        .maxTexelOffset                           = 7,
> >        .minTexelGatherOffset                     = -8,
> >        .maxTexelGatherOffset                     = 7,
> > -      .minInterpolationOffset                   = 0, /* FIXME */
> > -      .maxInterpolationOffset                   = 0, /* FIXME */
> > -      .subPixelInterpolationOffsetBits          = 0, /* FIXME */
> > +      .minInterpolationOffset                   = -0.5,
> > +      .maxInterpolationOffset                   = 0.5,
> > +      .subPixelInterpolationOffsetBits          = 4,
>
> I looked and neither gen7_pipeline.c nor gen8_pipeline.c set the subpixel
> precision so we get a default of enum value 0 which is 8 bits.  We should
> probably be explicitly setting it to something.  I think 4 is probably fine
> but we should be seeing it.
>
I think you're talking about "​Vertex Sub Pixel Precision Select" in
3DSTATE_SF. Yes, we are setting a default value of zero which is 8 bits in
both OpenGL and Vulkan. This meets the minimum requirement of 4 bits
for GL_SUBPIXEL_BITS. Yes, it'll be nicer to make it more obvious what we
are setting here.

The value we are defining in this patch is subPixelInterpolationOffsetBits
(GL_FRAGMENT_INTERPOLATION_OFFSET_BITS in OpenGL). I found no option of
setting it on Intel Hardware. I just replicated what we do in i965 and made
the CTS test happy again.

Looks unrelated but there is this another thing 'viewportSubPixelBits'
which is initialized to 13 in Vulkan but 0 (required min. value) in i965.
Again found no option of setting on Intel hardware.So, a similar case
to subPixelInterpolationOffsetBits.

> As a side note, I think we could probably combine 3DSTATE_SF and
> 3DSTATE_RASTER setup between gen7 and gen8 (and move it to
> genX_pipeline_until.h).  We'd probably have to do some #define trick like
> we did for 3DSTATE_SBE and 3DSTATE_SBE_SWIZ because the two packets are
> combined on gen7 and split on gen8.
>
​I'll look in to it.​


> >        .maxFramebufferWidth                      = (1 << 14),
> >        .maxFramebufferHeight                     = (1 << 14),
> >        .maxFramebufferLayers                     = (1 << 10),
> > --
> > 2.5.5
> >
>
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