[PATCH v7 1/2] drm/buddy: Add start address support to trim function

[Jani Nikula]

On Tue, 23 Jul 2024, Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam at amd.com> wrote:
> - Add a new start parameter in trim function to specify exact
>   address from where to start the trimming. This would help us
>   in situations like if drivers would like to do address alignment
>   for specific requirements.
>
> - Add a new flag DRM_BUDDY_TRIM_DISABLE. Drivers can use this
>   flag to disable the allocator trimming part. This patch enables
>   the drivers control trimming and they can do it themselves
>   based on the application requirements.
>
> v1:(Matthew)
>   - check new_start alignment with min chunk_size
>   - use range_overflows()
>
> Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam at amd.com>
> Acked-by: Alex Deucher <alexander.deucher at amd.com>
> Acked-by: Christian König <christian.koenig at amd.com>
> ---
>  drivers/gpu/drm/drm_buddy.c          | 25 +++++++++++++++++++++++--
>  drivers/gpu/drm/xe/xe_ttm_vram_mgr.c |  2 +-
>  include/drm/drm_buddy.h              |  2 ++
>  3 files changed, 26 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c
> index 6a8e45e9d0ec..103c185bb1c8 100644
> --- a/drivers/gpu/drm/drm_buddy.c
> +++ b/drivers/gpu/drm/drm_buddy.c
> @@ -851,6 +851,7 @@ static int __alloc_contig_try_harder(struct drm_buddy *mm,
>   * drm_buddy_block_trim - free unused pages
>   *
>   * @mm: DRM buddy manager
> + * @start: start address to begin the trimming.
>   * @new_size: original size requested
>   * @blocks: Input and output list of allocated blocks.
>   * MUST contain single block as input to be trimmed.
> @@ -866,11 +867,13 @@ static int __alloc_contig_try_harder(struct drm_buddy *mm,
>   * 0 on success, error code on failure.
>   */
>  int drm_buddy_block_trim(struct drm_buddy *mm,
> +			 u64 *start,

Is this a pointer only to allow passing NULL as "don't specify"? It's
not used for returning anything in *start. Maybe it should be a const
pointer?

Not the prettiest of interfaces, and the kernel-doc does not reflect any
of this.

BR,
Jani.


>  			 u64 new_size,
>  			 struct list_head *blocks)
>  {
>  	struct drm_buddy_block *parent;
>  	struct drm_buddy_block *block;
> +	u64 block_start, block_end;
>  	LIST_HEAD(dfs);
>  	u64 new_start;
>  	int err;
> @@ -882,6 +885,9 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>  				 struct drm_buddy_block,
>  				 link);
>  
> +	block_start = drm_buddy_block_offset(block);
> +	block_end = block_start + drm_buddy_block_size(mm, block);
> +
>  	if (WARN_ON(!drm_buddy_block_is_allocated(block)))
>  		return -EINVAL;
>  
> @@ -894,6 +900,20 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>  	if (new_size == drm_buddy_block_size(mm, block))
>  		return 0;
>  
> +	new_start = block_start;
> +	if (start) {
> +		new_start = *start;
> +
> +		if (new_start < block_start)
> +			return -EINVAL;
> +
> +		if (!IS_ALIGNED(new_start, mm->chunk_size))
> +			return -EINVAL;
> +
> +		if (range_overflows(new_start, new_size, block_end))
> +			return -EINVAL;
> +	}
> +
>  	list_del(&block->link);
>  	mark_free(mm, block);
>  	mm->avail += drm_buddy_block_size(mm, block);
> @@ -904,7 +924,6 @@ int drm_buddy_block_trim(struct drm_buddy *mm,
>  	parent = block->parent;
>  	block->parent = NULL;
>  
> -	new_start = drm_buddy_block_offset(block);
>  	list_add(&block->tmp_link, &dfs);
>  	err =  __alloc_range(mm, &dfs, new_start, new_size, blocks, NULL);
>  	if (err) {
> @@ -1066,7 +1085,8 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>  	} while (1);
>  
>  	/* Trim the allocated block to the required size */
> -	if (original_size != size) {
> +	if (!(flags & DRM_BUDDY_TRIM_DISABLE) &&
> +	    original_size != size) {
>  		struct list_head *trim_list;
>  		LIST_HEAD(temp);
>  		u64 trim_size;
> @@ -1083,6 +1103,7 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>  		}
>  
>  		drm_buddy_block_trim(mm,
> +				     NULL,
>  				     trim_size,
>  				     trim_list);
>  
> diff --git a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
> index fe3779fdba2c..423b261ea743 100644
> --- a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
> +++ b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
> @@ -150,7 +150,7 @@ static int xe_ttm_vram_mgr_new(struct ttm_resource_manager *man,
>  	} while (remaining_size);
>  
>  	if (place->flags & TTM_PL_FLAG_CONTIGUOUS) {
> -		if (!drm_buddy_block_trim(mm, vres->base.size, &vres->blocks))
> +		if (!drm_buddy_block_trim(mm, NULL, vres->base.size, &vres->blocks))
>  			size = vres->base.size;
>  	}
>  
> diff --git a/include/drm/drm_buddy.h b/include/drm/drm_buddy.h
> index 2a74fa9d0ce5..9689a7c5dd36 100644
> --- a/include/drm/drm_buddy.h
> +++ b/include/drm/drm_buddy.h
> @@ -27,6 +27,7 @@
>  #define DRM_BUDDY_CONTIGUOUS_ALLOCATION		BIT(2)
>  #define DRM_BUDDY_CLEAR_ALLOCATION		BIT(3)
>  #define DRM_BUDDY_CLEARED			BIT(4)
> +#define DRM_BUDDY_TRIM_DISABLE			BIT(5)
>  
>  struct drm_buddy_block {
>  #define DRM_BUDDY_HEADER_OFFSET GENMASK_ULL(63, 12)
> @@ -155,6 +156,7 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm,
>  			   unsigned long flags);
>  
>  int drm_buddy_block_trim(struct drm_buddy *mm,
> +			 u64 *start,
>  			 u64 new_size,
>  			 struct list_head *blocks);
>  
>
> base-commit: b27d70e1042bf6a31ba7e5acf58b61c9cd28f95b

-- 
Jani Nikula, Intel