[PATCH v7 1/2] drm/buddy: Add start address support to trim function
Christian König
ckoenig.leichtzumerken at gmail.com
Wed Jul 24 11:20:33 UTC 2024
Am 24.07.24 um 11:37 schrieb Matthew Auld:
> On 24/07/2024 02:35, Marek Olšák wrote:
>> The reason is that our DCC requires 768K alignment in some cases. I
>> haven't read this patch series, but one way to do that is to align to
>> 256K, overallocate by 512K, and then not use either 0, 256K, or 512K
>> at the beginning to get to 768K alignment.
>
> Ah, so we need a non power-of-two alignment. That makes sense, thanks.
Well actually the requirement is that memory reads for scanout needs to
be distributed over the memory channels in a certain way.
Our hw guys just expressed that as a rather strange non-power of two
alignment :)
Christian.
>
>>
>> Marek
>>
>> On Tue, Jul 23, 2024, 11:04 Matthew Auld <matthew.auld at intel.com
>> <mailto:matthew.auld at intel.com>> wrote:
>>
>> On 23/07/2024 14:43, Paneer Selvam, Arunpravin wrote:
>> > Hi Matthew,
>> >
>> > Can we push this version for now as we need to mainline the DCC
>> changes
>> > ASAP,
>> > while we continue our discussion and proceed to implement the
>> permanent
>> > solution
>> > for address alignment?
>>
>> Yeah, we can always merge now and circle back around later, if
>> this for
>> sure helps your usecase and is needed asap. I just didn't fully
>> get the
>> idea for needing this interface, but likely I am missing something.
>>
>> >
>> > Thanks,
>> > Arun.
>> >
>> > On 7/23/2024 6:55 PM, Arunpravin Paneer Selvam 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
>> <mailto:Arunpravin.PaneerSelvam at amd.com>>
>> >> Acked-by: Alex Deucher <alexander.deucher at amd.com
>> <mailto:alexander.deucher at amd.com>>
>> >> Acked-by: Christian König <christian.koenig at amd.com
>> <mailto: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,
>> >> 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
>> >
>>
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