[AMD Official Use Only - General]
>> Then a TLB flush shouldn't be necessary on reset. A reset implies that the
>> TLB is cleared as well.
Hmm, in current implementation, when we say a reset implied that the TLB is
cleared, assume that the TLB clear is purely hardware action. There's no gpu
tlb flush initiated by software/driver after suspend.
While in some asics of gfx11 (like nv31), gpu tlb need to be flushed by
software/driver after smu resume successfully intentionally.
Without the gpu tlb flush on nv31, S3 or reset will be break with gfx page
fault.
>> First of all the patch is broken because you only handle the locking, but
>> not the unlocking part.
For the unlocking part, realized that you and Kevin are correct. I should put
the trylock checking on the right of && to make sure it will be checked
firstly. Otherwise lock/unlock not paried.
Thanks,
Feifei
-----Original Message-----
From: Christian König <ckoenig.leichtzumer...@gmail.com>
Sent: Monday, October 9, 2023 4:52 PM
To: Xu, Feifei <feifei...@amd.com>; Wang, Yang(Kevin) <kevinyang.w...@amd.com>;
amd-gfx@lists.freedesktop.org
Cc: Koenig, Christian <christian.koe...@amd.com>; Zhang, Hawking
<hawking.zh...@amd.com>
Subject: Re: [PATCH] drm/amdgpu:Check gfx poweron when skip flush_gpu_tlb
Am 09.10.23 um 03:50 schrieb Xu, Feifei:
> [AMD Official Use Only - General]
>
> Hi,
>
>>> Based on your description, the above code should use "||" instead of
>>> "&&",
> && is to add more restriction here. To avoid skipping necessary TLB flush by
> return.
> For Asics < GFX11, !adev->gfx.is_poweron is always true (this
> paremeter is intrudoced from GFX11), only depends on reset_domain->sem; For
> Asics = GFX11, !adev->gfx.is_poweron might be false (which gfx might already
> poweron in the reset), this will make the if () not ture, return will not be
> executed, thus flush TLB.
First of all the patch is broken because you only handle the locking, but not
the unlocking part.
Then a TLB flush shouldn't be necessary on reset. A reset implies that the TLB
is cleared as well.
We discussed the possibility to avoid that, but this is not supposed to be
happening at the moment.
Regards,
Christian.
>
>>> And after merging code into one line may result in the lock not being
>>> released if the lock can be acquired success.
> If !adev->gfx.is_poweron is true, the reset_domin->sem will not be
> down_read_trylock, thus could avoid this deadlock.
>
> Thanks,
> Feifei
>
> -----Original Message-----
> From: Wang, Yang(Kevin) <kevinyang.w...@amd.com>
> Sent: Sunday, October 8, 2023 9:36 PM
> To: Xu, Feifei <feifei...@amd.com>; amd-gfx@lists.freedesktop.org
> Cc: Xu, Feifei <feifei...@amd.com>; Xu, Feifei <feifei...@amd.com>;
> Koenig, Christian <christian.koe...@amd.com>; Zhang, Hawking
> <hawking.zh...@amd.com>
> Subject: RE: [PATCH] drm/amdgpu:Check gfx poweron when skip
> flush_gpu_tlb
>
>
> -----Original Message-----
> From: amd-gfx <amd-gfx-boun...@lists.freedesktop.org> On Behalf Of
> Feifei Xu
> Sent: Sunday, October 8, 2023 6:07 PM
> To: amd-gfx@lists.freedesktop.org
> Cc: Xu, Feifei <feifei...@amd.com>; Xu, Feifei <feifei...@amd.com>;
> Koenig, Christian <christian.koe...@amd.com>; Zhang, Hawking
> <hawking.zh...@amd.com>
> Subject: [PATCH] drm/amdgpu:Check gfx poweron when skip flush_gpu_tlb
>
> To fix the gpu recovery failed on GFX11 with gfxhub pagefault, flush gpu tlb
> after reset on GFX11.
> Gfxhub tlb flush need check if adev->gfx.is_poweron set.
>
> Fixes: d0c860f33553 ("drm/amdgpu: rework lock handling for flush_tlb
> v2")
>
> Signed-off-by: Feifei Xu <feifei...@amd.com>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
> index 2f9bb86edd71..048d32edee88 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
> @@ -611,8 +611,9 @@ void amdgpu_gmc_flush_gpu_tlb(struct amdgpu_device *adev,
> uint32_t vmid,
> /*
> * A GPU reset should flush all TLBs anyway, so no need to do
> * this while one is ongoing.
> + * For GFX11, gfxhub flush check if adev->gfx.is_poweron is
> set.
> */
> - if (!down_read_trylock(&adev->reset_domain->sem))
> + if (!down_read_trylock(&adev->reset_domain->sem) &&
> +!adev->gfx.is_poweron)
> return;
>
> [Kevin]:
> Based on your description, the above code should use "||" instead of
> "&&", And after merging code into one line may result in the lock not being
> released if the lock can be acquired success.
>
> Best Regards,
> Kevin
>
> if (adev->gmc.flush_tlb_needs_extra_type_2)
> --
> 2.34.1
>
