[PATCH] drm/amdgpu: Limit the maximum size of contiguous VRAM that can be encapsulated by an instance of DRM memory node

[Christian König]

Am 28.01.21 um 18:43 schrieb Ramesh Errabolu:
> [Why]
> Enable 1:1 mapping between VRAM of a DRM node and a scatterlist node
>
> [How]
> Ensure construction of DRM node to not exceed specified limit
>
> Signed-off-by: Ramesh Errabolu <Ramesh.Errabolu at amd.com>

Reviewed-by: Christian König <christian.koenig at amd.com>

> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 3 +++
>   1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> index 20747d8b1135..21d18efca277 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> @@ -476,6 +476,9 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
>   	for (i = 0; pages_left >= pages_per_node; ++i) {
>   		unsigned long pages = rounddown_pow_of_two(pages_left);
>   
> +		/* Limit maximum size to 2GB due to SG table limitations */
> +		pages = min(pages, (2UL << (30 - PAGE_SHIFT)));
> +
>   		r = drm_mm_insert_node_in_range(mm, &nodes[i], pages,
>   						pages_per_node, 0,
>   						place->fpfn, lpfn,