[RFC PATCH 1/1] drm/amdgpu: fix usable gart size calculation

[Christian König]

Am 13.11.20 um 17:17 schrieb Nirmoy Das:
> amdgpu_do_test_moves() is failing because of wrong
> usable gart size calculation and throwing:
>
> [drm:amdgpu_do_test_moves [amdgpu]] *ERROR* 0000000020bdc9f3 bind failed
>
> Signed-off-by: Nirmoy Das <nirmoy.das at amd.com>
> ---
>
> This still doesn't work. As per my calculation 1st 4MB of GART is not
> accounted for in adev->gmc.gart_size - atomic64_read(&adev->gart_pin_size).

The member gart_pin_size should probably be renamed to gtt_pin_size, but 
since a gtt pin is also automatically visible in the GART that should 
probably be ok for now.

> What am I missing ?

The two 2MB windows in the GART which are used for buffer moves.

See AMDGPU_GTT_MAX_TRANSFER_SIZE and AMDGPU_GTT_NUM_TRANSFER_WINDOWS.

Regards,
Christian.

>
>   drivers/gpu/drm/amd/amdgpu/amdgpu_test.c | 11 ++---------
>   1 file changed, 2 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_test.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_test.c
> index 6042b3b81a4c..d983c729997f 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_test.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_test.c
> @@ -42,16 +42,9 @@ static void amdgpu_do_test_moves(struct amdgpu_device *adev)
>   	size = 1024 * 1024;
>
>   	/* Number of tests =
> -	 * (Total GTT - IB pool - writeback page - ring buffers) / test size
> +	 * (Total GTT - gart_pin_size) / test size
>   	 */
> -	n = adev->gmc.gart_size - AMDGPU_IB_POOL_SIZE;
> -	for (i = 0; i < AMDGPU_MAX_RINGS; ++i)
> -		if (adev->rings[i])
> -			n -= adev->rings[i]->ring_size;
> -	if (adev->wb.wb_obj)
> -		n -= AMDGPU_GPU_PAGE_SIZE;
> -	if (adev->irq.ih.ring_obj)
> -		n -= adev->irq.ih.ring_size;
> +	n = adev->gmc.gart_size - atomic64_read(&adev->gart_pin_size);
>   	n /= size;
>
>   	gtt_obj = kcalloc(n, sizeof(*gtt_obj), GFP_KERNEL);
> --
> 2.29.0
>
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