[PATCH] drm/amdgpu: Account for shadow PTs in mapping update IB size.

[Christian König]

Am 07.09.2017 um 13:23 schrieb Bas Nieuwenhuizen:
> When amdgpu_vm_frag_ptes calls amdgpu_vm_update_ptes and the pt
> has a shadow PT we mirror all the write to the shadow PT too, which
> results in twice the commands.
>
> Signed-off-by: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>

Good catch. Patch is Reviewed-by: Christian König <christian.koenig at amd.com>

> ---
>
> The current patch is quite pessimistic, maybe someone familiar with the
> code knows a better set of conditions.
>
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> index 09811b2b89fe..22f5007d6821 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> @@ -1547,10 +1547,12 @@ static int amdgpu_vm_bo_update_mapping(struct amdgpu_device *adev,
>   	nptes = last - start + 1;
>   
>   	/*
> -	 * reserve space for one command every (1 << BLOCK_SIZE)
> +	 * reserve space for two commands every (1 << BLOCK_SIZE)
>   	 *  entries or 2k dwords (whatever is smaller)
> +         *
> +         * The second command is for the shadow pagetables.
>   	 */
> -	ncmds = (nptes >> min(adev->vm_manager.block_size, 11u)) + 1;
> +	ncmds = ((nptes >> min(adev->vm_manager.block_size, 11u)) + 1) * 2;
>   
>   	/* padding, etc. */
>   	ndw = 64;