[PATCH] drm/amdgpu: Fix the vram base start address

[Christian König]

Am 30.10.23 um 13:22 schrieb Arunpravin Paneer Selvam:
> If the size returned by drm buddy allocator is higher than
> the required size, we take the higher size to calculate
> the buffer start address. This is required if we couldn't
> trim the buffer to the requested size. This will fix the
> display corruption issue on APU's which has limited VRAM
> size.
>
> gitlab issue link: https://gitlab.freedesktop.org/drm/amd/-/issues/2859
> JIRA ticket link: https://ontrack-internal.amd.com/browse/SWDEV-425461
>
> Fixes: 0a1844bf0b53 ("drm/buddy: Improve contiguous memory allocation")
> Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam at amd.com>

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

IIRC that hack with the start address is actually not needed any more, 
but we need to double check this.

Christian.

> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 15 +++++++++++++--
>   1 file changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> index 18f58efc9dc7..08916538a615 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> @@ -77,7 +77,16 @@ static inline bool amdgpu_is_vram_mgr_blocks_contiguous(struct list_head *head)
>   	return true;
>   }
>   
> +static inline u64 amdgpu_vram_mgr_blocks_size(struct list_head *head)
> +{
> +	struct drm_buddy_block *block;
> +	u64 size = 0;
>   
> +	list_for_each_entry(block, head, link)
> +		size += amdgpu_vram_mgr_block_size(block);
> +
> +	return size;
> +}
>   
>   /**
>    * DOC: mem_info_vram_total
> @@ -516,6 +525,8 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
>   	mutex_unlock(&mgr->lock);
>   
>   	vres->base.start = 0;
> +	size = max_t(u64, amdgpu_vram_mgr_blocks_size(&vres->blocks),
> +		     vres->base.size);
>   	list_for_each_entry(block, &vres->blocks, link) {
>   		unsigned long start;
>   
> @@ -523,8 +534,8 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
>   			amdgpu_vram_mgr_block_size(block);
>   		start >>= PAGE_SHIFT;
>   
> -		if (start > PFN_UP(vres->base.size))
> -			start -= PFN_UP(vres->base.size);
> +		if (start > PFN_UP(size))
> +			start -= PFN_UP(size);
>   		else
>   			start = 0;
>   		vres->base.start = max(vres->base.start, start);