Re: [PATCH] drm/buddy: Add start address support to trim function

["Paneer Selvam, Arunpravin" <arunpravin.paneerselvam@amd.com>]

Thanks Alex.

Hi Matthew,
Any comments?

Thanks,
Arun.

On 7/9/2024 1:42 AM, Alex Deucher wrote:
> On Thu, Jul 4, 2024 at 4:40 AM Arunpravin Paneer Selvam
> <Arunpravin.PaneerSelvam@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@amd.com>
> Series is:
> Acked-by: Alex Deucher <alexander.deucher@amd.com>
>
> I'd like to take this series through the amdgpu tree if there are no
> objections as it's required for display buffers on some chips and I'd
> like to make sure it lands in 6.11.
>
> Thanks,
>
> Alex
>
>> ---
>>   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 94f8c34fc293..8cebe1fa4e9d 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,
>>                           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 82570f77e817..0c2f735f0265 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);
>>
>> --
>> 2.25.1
>>