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

[Anuj Phogat]

On Fri, Jul 29, 2016 at 12:32 PM, Anuj Phogat <anuj.phogat at gmail.com> wrote:

>
>
> 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,
>>
> Correction: ​maxInterpolationOffset = 0.4375
>From Vulkan 1.0 spec:
​"
If subPixelInterpolationOffsetBits is 4, this provides increments of (1/24)
= 0.0625, and thus the range of supported interpolation offsets would be
[-0.5, 0.4375].
​"
​

> > +      .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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