[Mesa-dev] [PATCH] svga: fix blending regression

[Ilia Mirkin]

Ok. Is there a test that failed? I'll probably have to fix up nv50 for it.

On Mar 1, 2018 11:43 AM, "Brian Paul" <brianp at vmware.com> wrote:

> On 02/28/2018 08:36 AM, Ilia Mirkin wrote:
>
>> Can st/mesa instead be fixed to maintain the original API? Other
>> drivers look in rt[0] in the non-independent_blend_enable case. For
>> example, freedreno and nouveau.
>>
>
> If independent blend is not in use, then rt[0] will have all the blending
> info, as before.
>
> The case that broke for us was when PIPE_CAP_INDEP_BLEND_FUNC==0 and
> independent blend was enabled for rt[i] where i > 0.  Before, the blend
> src/dst terms were in rt[0] but now they're in rt[i].
>
> I'd rather not change the semantics again.
>
> -Brian
>
>
>> On Wed, Feb 28, 2018 at 10:29 AM, Brian Paul <brianp at vmware.com> wrote:
>>
>>> The earlier Mesa commit 3d06c8afb5 ("st/mesa: don't translate blend
>>> state when it's disabled for a colorbuffer") subtly changed the
>>> details of gallium's per-RT blend state.
>>>
>>> In particular, when pipe_rt_blend_state[i].blend_enabled is true,
>>> we have to get the src/dst blend terms from pipe_rt_blend_state[i],
>>> not [0] as before.
>>>
>>> We now have to scan the blend targets to find the first one that's
>>> enabled (if any).  We have to use the index of that target for getting
>>> the src/dst blend terms.  And note that we have to set identical blend
>>> terms for all targets.
>>>
>>> This fixes the Piglit fbo-drawbuffers2-blend test.  VMware bug 2063493.
>>> ---
>>>   src/gallium/drivers/svga/svga_pipe_blend.c | 35
>>> ++++++++++++++++++++----------
>>>   1 file changed, 24 insertions(+), 11 deletions(-)
>>>
>>> diff --git a/src/gallium/drivers/svga/svga_pipe_blend.c
>>> b/src/gallium/drivers/svga/svga_pipe_blend.c
>>> index 04855fa..6bb9d94 100644
>>> --- a/src/gallium/drivers/svga/svga_pipe_blend.c
>>> +++ b/src/gallium/drivers/svga/svga_pipe_blend.c
>>> @@ -148,6 +148,17 @@ svga_create_blend_state(struct pipe_context *pipe,
>>>      if (!blend)
>>>         return NULL;
>>>
>>> +   /* Find index of first target with blending enabled.  -1 means
>>> blending
>>> +    * is not enabled at all.
>>> +    */
>>> +   int first_enabled = -1;
>>> +   for (i = 0; i < PIPE_MAX_COLOR_BUFS; i++) {
>>> +      if (templ->rt[i].blend_enable) {
>>> +         first_enabled = i;
>>> +         break;
>>> +      }
>>> +   }
>>> +
>>>      /* Fill in the per-rendertarget blend state.  We currently only
>>>       * support independent blend enable and colormask per render target.
>>>       */
>>> @@ -260,24 +271,26 @@ svga_create_blend_state(struct pipe_context *pipe,
>>>            }
>>>         }
>>>         else {
>>> -         /* Note: the vgpu10 device does not yet support independent
>>> -          * blend terms per render target.  Target[0] always specifies
>>> the
>>> -          * blending terms.
>>> +         /* Note: the vgpu10 device does not yet support independent
>>> blend
>>> +          * terms per render target.  When blending is enabled, the
>>> blend
>>> +          * terms must match for all targets.
>>>             */
>>> -         if (templ->independent_blend_enable ||
>>> templ->rt[0].blend_enable) {
>>> -            /* always use the 0th target's blending terms for now */
>>> +         if (first_enabled >= 0) {
>>> +            /* use first enabled target's blending terms */
>>> +            const struct pipe_rt_blend_state *rt =
>>> &templ->rt[first_enabled];
>>> +
>>>               blend->rt[i].srcblend =
>>> -               svga_translate_blend_factor(svga,
>>> templ->rt[0].rgb_src_factor);
>>> +               svga_translate_blend_factor(svga, rt->rgb_src_factor);
>>>               blend->rt[i].dstblend =
>>> -               svga_translate_blend_factor(svga,
>>> templ->rt[0].rgb_dst_factor);
>>> +               svga_translate_blend_factor(svga, rt->rgb_dst_factor);
>>>               blend->rt[i].blendeq =
>>> -               svga_translate_blend_func(templ->rt[0].rgb_func);
>>> +               svga_translate_blend_func(rt->rgb_func);
>>>               blend->rt[i].srcblend_alpha =
>>> -               svga_translate_blend_factor(svga,
>>> templ->rt[0].alpha_src_factor);
>>> +               svga_translate_blend_factor(svga, rt->alpha_src_factor);
>>>               blend->rt[i].dstblend_alpha =
>>> -               svga_translate_blend_factor(svga,
>>> templ->rt[0].alpha_dst_factor);
>>> +               svga_translate_blend_factor(svga, rt->alpha_dst_factor);
>>>               blend->rt[i].blendeq_alpha =
>>> -               svga_translate_blend_func(templ->rt[0].alpha_func);
>>> +               svga_translate_blend_func(rt->alpha_func);
>>>
>>>               if (blend->rt[i].srcblend_alpha != blend->rt[i].srcblend ||
>>>                   blend->rt[i].dstblend_alpha != blend->rt[i].dstblend ||
>>> --
>>> 2.7.4
>>>
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>>
>
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