[PATCH] drm/amdgpu: only WARN freeing buffers when DMA is unavailable

[Christian König]

Am 06.02.23 um 08:23 schrieb Xiao, Jack:
>
> [AMD Official Use Only - General]
>
> >> Nope, that is not related to any hw state.
>
> can use other flag.
>
> >> It's simply not allowed to free up resources during suspend since 
> those can't be acquired again during resume.
>
> The in_suspend flag is set at the beginning of suspend and unset at 
> the end of resume. It can’t filter the case you mentioned.
>

Why not? This is exactly what it should do.

> Do you know the root cause of these cases hitting the issue? So that 
> we can get an exact point to warn the freeing up behavior.
>

Well the root cause are programming errors. See between suspending and 
resuming you should not allocate nor free memory.

Otherwise we can run into trouble. And this check here is one part of 
that, we should probably add another warning during allocation of 
memory. But this here is certainly correct.

Regards,
Christian.

> Thanks,
>
> Jack
>
> *From:* Christian König <ckoenig.leichtzumerken at gmail.com>
> *Sent:* Friday, February 3, 2023 9:20 PM
> *To:* Xiao, Jack <Jack.Xiao at amd.com>; Koenig, Christian 
> <Christian.Koenig at amd.com>; amd-gfx at lists.freedesktop.org; Deucher, 
> Alexander <Alexander.Deucher at amd.com>
> *Subject:* Re: [PATCH] drm/amdgpu: only WARN freeing buffers when DMA 
> is unavailable
>
> Nope, that is not related to any hw state.
>
> It's simply not allowed to free up resources during suspend since 
> those can't be acquired again during resume.
>
> We had a couple of cases now where this was wrong. If you get a 
> warning from that please fix the code which tried to free something 
> during suspend instead.
>
> Regards,
> Christian.
>
> Am 03.02.23 um 07:04 schrieb Xiao, Jack:
>
>     [AMD Official Use Only - General]
>
>     >> It's simply illegal to free up memory during suspend.
>
>     Why? In my understanding, the limit was caused by DMA shutdown.
>
>     Regards,
>
>     Jack
>
>     *From:* Koenig, Christian <Christian.Koenig at amd.com>
>     <mailto:Christian.Koenig at amd.com>
>     *Sent:* Thursday, February 2, 2023 7:43 PM
>     *To:* Xiao, Jack <Jack.Xiao at amd.com> <mailto:Jack.Xiao at amd.com>;
>     amd-gfx at lists.freedesktop.org; Deucher, Alexander
>     <Alexander.Deucher at amd.com> <mailto:Alexander.Deucher at amd.com>
>     *Subject:* AW: [PATCH] drm/amdgpu: only WARN freeing buffers when
>     DMA is unavailable
>
>     Big NAK to this! This warning is not related in any way to the hw
>     state.
>
>     It's simply illegal to free up memory during suspend.
>
>     Regards,
>
>     Christian.
>
>     ------------------------------------------------------------------------
>
>     *Von:*Xiao, Jack <Jack.Xiao at amd.com>
>     *Gesendet:* Donnerstag, 2. Februar 2023 10:54
>     *An:* amd-gfx at lists.freedesktop.org
>     <amd-gfx at lists.freedesktop.org>; Deucher, Alexander
>     <Alexander.Deucher at amd.com>; Koenig, Christian
>     <Christian.Koenig at amd.com>
>     *Cc:* Xiao, Jack <Jack.Xiao at amd.com>
>     *Betreff:* [PATCH] drm/amdgpu: only WARN freeing buffers when DMA
>     is unavailable
>
>     Reduce waringings, only warn when DMA is unavailable.
>
>     Signed-off-by: Jack Xiao <Jack.Xiao at amd.com>
>     ---
>      drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 3 ++-
>      1 file changed, 2 insertions(+), 1 deletion(-)
>
>     diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
>     b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
>     index 2d237f3d3a2e..e3e3764ea697 100644
>     --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
>     +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
>     @@ -422,7 +422,8 @@ void amdgpu_bo_free_kernel(struct amdgpu_bo
>     **bo, u64 *gpu_addr,
>              if (*bo == NULL)
>                      return;
>
>     - WARN_ON(amdgpu_ttm_adev((*bo)->tbo.bdev)->in_suspend);
>     + WARN_ON(amdgpu_ttm_adev((*bo)->tbo.bdev)->in_suspend &&
>     +
>     !amdgpu_ttm_adev((*bo)->tbo.bdev)->ip_blocks[AMD_IP_BLOCK_TYPE_SDMA].status.hw);
>
>              if (likely(amdgpu_bo_reserve(*bo, true) == 0)) {
>                      if (cpu_addr)
>     -- 
>     2.37.3
>
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