[Mesa-dev] [PATCH] Revert "i915: Always enable GL 2.0 support."

[Eero Tamminen]

Hi,

On 31.01.2017 21:12, Matt Turner wrote:
> On Sun, Jan 29, 2017 at 8:29 PM, Kenneth Graunke <kenneth at whitecape.org> wrote:
>> On Sunday, January 29, 2017 6:20:10 PM PST Matt Turner wrote:
>>> This partially reverts commit 97217a40f97cdeae0304798b607f704deb0c3558.
>>> It leaves ES 2.0 support in place per Ian's suggestion, because ES 2.0
>>> is designed to work on hardware like i915.
>>
>> Your commit message should mention why dropping from OpenGL 2.1 to 1.4
>> is a good thing.
>>
>> (IIRC it's because Chrome (and other apps?) use really slow paths with
>> 2.1, and so the general usability of the system is likely to be worse.)
 >
> Yeah, I'll add

Has that been profiled?  I assume the issue is the constant uploads 
Chrome does for the Browser's CPU rendered page content updates.  There 
are not many other workloads that utilize GPU as inefficiently as 
current browsers.


	- Eero

> Chrome only uses the GPU if you have GL >= 2.0, and using i915 (and
> prog_execute) actually hurt performance compared with the software
> paths.
 >
>>> The piglit results look like:
>>>
>>>        name: before-revert-i915 after-revert-i915
>>>        ----  ------------------ -----------------
>>>        pass:               7171              2169
>>>        fail:                933               201
>>>       crash:                  8                 7
>>>        skip:              32997             38676
>>>     timeout:                  0                 0
>>>        warn:                  3                 1
>>>  incomplete:                  0                 0
>>>  dmesg-warn:                  0                 0
>>>  dmesg-fail:                  0                 0
>>>     changes:                  0              6040
>>>       fixes:                  0               292
>>> regressions:                  0                 2
>>>       total:              41112             41054
>>
>> Why are these interesting?
>
> I thought it was interesting to see that GL 2.1 support actually
> regressed 292 tests of GL 1.0 and 1.1 functionality (most of them in
> spec/!opengl 1.1/clipflat/). I can remove it from the commit message.
>
>>
>>> Cc: "17.0" <mesa-stable at lists.freedesktop.org>
>>> ---
>>>  src/mesa/drivers/dri/i915/intel_extensions.c |  8 ++++++--
>>>  src/mesa/drivers/dri/i915/intel_screen.c     | 21 +++++++++++++++++++--
>>>  2 files changed, 25 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/src/mesa/drivers/dri/i915/intel_extensions.c b/src/mesa/drivers/dri/i915/intel_extensions.c
>>> index ab7820f..4f2c6fa 100644
>>> --- a/src/mesa/drivers/dri/i915/intel_extensions.c
>>> +++ b/src/mesa/drivers/dri/i915/intel_extensions.c
>>> @@ -92,8 +92,12 @@ intelInitExtensions(struct gl_context *ctx)
>>>        ctx->Extensions.ATI_separate_stencil = true;
>>>        ctx->Extensions.ATI_texture_env_combine3 = true;
>>>        ctx->Extensions.NV_texture_env_combine4 = true;
>>> -      ctx->Extensions.ARB_fragment_shader = true;
>>> -      ctx->Extensions.ARB_occlusion_query = true;
>>> +
>>> +      if (driQueryOptionb(&intel->optionCache, "fragment_shader"))
>>> +         ctx->Extensions.ARB_fragment_shader = true;
>>
>> I get dropping GLSL support, but isn't GL_ARB_fragment_shader sort of
>> reasonable for this hardware?
>
> I don't know. I'm just reverting it to how it was before commit 97217a40f97cd.
>
> Ian, do you have an opinion?
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