[Mesa-dev] [PATCH] i965: Don't try to resolve CCS with MESA_FORMAT_NONE.

[Jason Ekstrand]

I just pushed this patch:

https://patchwork.freedesktop.org/patch/158551/

Which is the "correct" fix.  I'll send out an ISL patch shortly that adds a
bunch more asserts and should make this sort of thing easier to catch in
the future.

On Mon, Jun 5, 2017 at 2:55 AM, Eero Tamminen <eero.t.tamminen at intel.com>
wrote:

> Hi,
>
> On 04.06.2017 22:26, Kenneth Graunke wrote:
>
>> Since commit e9f5004d5ea38a21019e0affcd63d353b98d499a, KDE's Plasma
>> Shell started crashing when intel_disable_rb_aux_buffer tried to
>> dereference irb->mt, and there was no miptree.  This happened during
>> intel_texture_view_requires_resolve, coming from a glClear().
>>
>
> That's not the only thing dying because of ISL_FORMAT_UNSUPPORTED.
>
> Most of the benchmarks are currently crashing on GEN9.
>
> GpuTest 0.7, GLBenchmark 2.7, Lightsmark2008, Unigine Heaven & Valley,
> SynMark and several GfxBench v4 test-cases (T-Rex, driver, driver2,
> blending, fill) crash because of ISL_FORMAT_UNSUPPORTED:
> -------------
> Program received signal SIGSEGV, Segmentation fault.
> 0x00007ffff24c35a1 in isl_format_supports_ccs_e (devinfo=0x7ce998,
> format=ISL_FORMAT_UNSUPPORTED)
>     at ../../../src/intel/isl/isl_format.c:536
> 536        if (!format_info[format].exists)
> -------------
>
> If latest Mesa is installed to the system instead of one running just the
> test-case it with, one gets for some of those BadWindow errors instead, and
> Ubuntu compiz also crashes.
>
>
>         - Eero
>
>
> Apparently intel_tex->_Format is MESA_FORMAT_NONE.  We used to translate
>> MESA_FORMAT_NONE to 0, which happens to be ISL_FORMAT_R32G32B32A32_FLOAT,
>> which happens to support CCS_E, so we assumed no resolves were needed.
>>
>> That patch began translating MESA_FORMAT_NONE as ISL_FORMAT_UNSUPPORTED,
>> which claims not to support CCS_E, so we thought we needed resolves,
>> even though the buffer was in a bad state.
>>
>> For now, detect intel_tex->_Format == MESA_FORMAT_NONE and bail, like
>> we used to.  This is an ugly band-aid fix, but that's okay, given that
>> Jason has patches on the mailing list to rewrite the resolve code.
>>
>> This makes KDE usable again.
>> ---
>>  src/mesa/drivers/dri/i965/brw_context.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/src/mesa/drivers/dri/i965/brw_context.c
>> b/src/mesa/drivers/dri/i965/brw_context.c
>> index 9878cae9d4b..d8219cb57e0 100644
>> --- a/src/mesa/drivers/dri/i965/brw_context.c
>> +++ b/src/mesa/drivers/dri/i965/brw_context.c
>> @@ -205,6 +205,9 @@ intel_texture_view_requires_resolve(struct
>> brw_context *brw,
>>         !intel_miptree_is_lossless_compressed(brw, intel_tex->mt))
>>       return false;
>>
>> +   if (intel_tex->_Format == MESA_FORMAT_NONE)
>> +      return false;
>> +
>>     const enum isl_format isl_format =
>>        brw_isl_format_for_mesa_format(intel_tex->_Format);
>>
>>
>>
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