[Mesa-dev] [PATCH 0/5] Enable up to 24 MRF registers in gen6

[Matt Turner]

On Mon, Sep 21, 2015 at 8:00 AM, Iago Toral <itoral at igalia.com> wrote:
> On Mon, 2015-09-21 at 07:49 -0700, Kenneth Graunke wrote:
>> On Monday, September 21, 2015 09:46:24 AM Mark Janes wrote:
>> > This series hits an assertion on ILK and G45:
>> >
>> > src/mesa/drivers/dri/i965/brw_eu_emit.c:150: brw_set_dest: Assertion
>> > `dest.nr < (devinfo->gen == 6 ? 24 : 16)' failed.
>> >
>> > It triggers about 8k piglit assertions on those platforms.  I'm turning
>> > off testing for G45 and ILK until it is resolved.
>> >
>> > https://bugs.freedesktop.org/show_bug.cgi?id=92066
>> >
>> > -Mark
>>
>> I've pushed a fix for this:
>>
>> commit c1070550c289d48ef389aeb8c564d1abd1123ad1
>> Author: Kenneth Graunke <kenneth at whitecape.org>
>> Date:   Mon Sep 21 07:42:27 2015 -0700
>>
>>     i965: Fix MRF register number assertions for compr4.
>>
>>     compr4 is represented by setting the high bit on the MRF number.
>>     We need to mask it out before sanity checking the register number.
>>
>>     Fixes ~8000 assert fails on Ironlake and G45.
>>
>>     Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=92066
>>     Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
>>
>> Easy mistake...I always forget about compr4.  Hopefully we should be
>> good now.
>
> that was fast, thanks Ken! I was scratching my head over this...
>
> BTW, I just noticed that the ILK docs also say that they have 24 MRFs...
> (volume 4, part 2, 5.3.3 MRF Registers). Assuming that we don't find any
> other issues, would we want to extend the fix to ILK too?

The ILK docs are notoriously bad and often contain more information
about Sandybridge than Ironlake. I suspect that information is
actually about SNB, though I suppose it couldn't hurt to try on ILK,
though I'm doubtful.