drm/amdgpu: apply AMDGPU_IB_FLAG_EMIT_MEM_SYNC to compute IBs too

[Marek Olšák]

PAL requested it and they are going to use it. (it looks like they have to
use it for correctness)

Marek

On Mon, Apr 27, 2020 at 9:02 AM Deucher, Alexander <
Alexander.Deucher at amd.com> wrote:

> [AMD Official Use Only - Internal Distribution Only]
>
> Do we have open source code UMD code which uses this?
>
> Alex
> ------------------------------
> *From:* Christian König <ckoenig.leichtzumerken at gmail.com>
> *Sent:* Sunday, April 26, 2020 4:55 AM
> *To:* Marek Olšák <maraeo at gmail.com>; Koenig, Christian <
> Christian.Koenig at amd.com>
> *Cc:* Deucher, Alexander <Alexander.Deucher at amd.com>; amd-gfx mailing
> list <amd-gfx at lists.freedesktop.org>
> *Subject:* Re: drm/amdgpu: apply AMDGPU_IB_FLAG_EMIT_MEM_SYNC to compute
> IBs too
>
> Thanks for that explanation. I suspected that there was a good reason to
> have that in the kernel, but couldn't find one.
>
> In this case the patch is Reviewed-by: Christian König
> <christian.koenig at amd.com> <christian.koenig at amd.com>
>
> We should probably add this explanation as comment to the flag as well.
>
> Thanks,
> Christian.
>
> Am 26.04.20 um 02:43 schrieb Marek Olšák:
>
> It was merged into amd-staging-drm-next.
>
> I'm not absolutely sure, but I think we need to invalidate before IBs if
> an IB is cached in L2 and the CPU has updated it. It can only be cached in
> L2 if something other than CP has read it or written to it without
> invalidation. CP reads don't cache it but they can hit the cache if it's
> already cached.
>
> For CE, we need to invalidate before the IB in the kernel, because CE IBs
> can't do cache invalidations IIRC. This is the number one reason for
> merging the already pushed commits.
>
> Marek
>
> On Sat., Apr. 25, 2020, 11:03 Christian König, <
> ckoenig.leichtzumerken at gmail.com> wrote:
>
> Was that patch set actually merged upstream? My last status is that we
> couldn't find a reason why we need to do this in the kernel.
>
> Christian.
>
> Am 25.04.20 um 10:52 schrieb Marek Olšák:
>
> This was missed.
>
> Marek
>
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