[PATCH] drm/amdgpu: Use iterator methods exposed by amdgpu_res_cursor.h in building SG_TABLE's for a VRAM BO
Alex Deucher
alexdeucher at gmail.com
Tue Apr 13 13:25:28 UTC 2021
On Mon, Apr 12, 2021 at 7:28 PM Ramesh Errabolu <Ramesh.Errabolu at amd.com> wrote:
>
> Extend current implementation of SG_TABLE construction method to
> allow exportation of sub-buffers of a VRAM BO. This capability will
> enable logical partitioning of a VRAM BO into multiple non-overlapping
> sub-buffers. One example of this use case is to partition a VRAM BO
> into two sub-buffers, one for SRC and another for DST.
>
> Signed-off-by: Ramesh Errabolu <Ramesh.Errabolu at amd.com>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c | 6 ++--
> drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h | 1 +
> drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 32 ++++++++++++++------
> 3 files changed, 27 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
> index e0c4f7c7f1b9..57534b93bd91 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
> @@ -255,6 +255,7 @@ static struct sg_table *amdgpu_dma_buf_map(struct dma_buf_attachment *attach,
> struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
> struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);
> struct sg_table *sgt;
> + u64 num_bytes;
> long r;
>
> if (!bo->tbo.pin_count) {
> @@ -291,8 +292,9 @@ static struct sg_table *amdgpu_dma_buf_map(struct dma_buf_attachment *attach,
> break;
>
> case TTM_PL_VRAM:
> - r = amdgpu_vram_mgr_alloc_sgt(adev, &bo->tbo.mem, attach->dev,
> - dir, &sgt);
> + num_bytes = bo->tbo.mem.num_pages << PAGE_SHIFT;
> + r = amdgpu_vram_mgr_alloc_sgt(adev, &bo->tbo.mem, 0, num_bytes,
> + attach->dev, dir, &sgt);
> if (r)
> return ERR_PTR(r);
> break;
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
> index dec0db8b0b13..9e38475e0f8d 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
> @@ -112,6 +112,7 @@ int amdgpu_gtt_mgr_recover(struct ttm_resource_manager *man);
> u64 amdgpu_vram_mgr_bo_visible_size(struct amdgpu_bo *bo);
> int amdgpu_vram_mgr_alloc_sgt(struct amdgpu_device *adev,
> struct ttm_resource *mem,
> + u64 offset, u64 size,
> struct device *dev,
> enum dma_data_direction dir,
> struct sg_table **sgt);
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> index 592a2dd16493..fcdee0deba16 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> @@ -25,6 +25,7 @@
> #include <linux/dma-mapping.h>
> #include "amdgpu.h"
> #include "amdgpu_vm.h"
> +#include "amdgpu_res_cursor.h"
> #include "amdgpu_atomfirmware.h"
> #include "atom.h"
>
> @@ -565,6 +566,8 @@ static void amdgpu_vram_mgr_del(struct ttm_resource_manager *man,
> *
> * @adev: amdgpu device pointer
> * @mem: TTM memory object
> + * @offset: byte offset from the base of VRAM BO
> + * @length: number of bytes to export in sg_table
> * @dev: the other device
> * @dir: dma direction
> * @sgt: resulting sg table
> @@ -573,39 +576,45 @@ static void amdgpu_vram_mgr_del(struct ttm_resource_manager *man,
> */
> int amdgpu_vram_mgr_alloc_sgt(struct amdgpu_device *adev,
> struct ttm_resource *mem,
> + u64 offset, u64 length,
> struct device *dev,
> enum dma_data_direction dir,
> struct sg_table **sgt)
> {
> - struct drm_mm_node *node;
> + struct amdgpu_res_cursor cursor;
> struct scatterlist *sg;
> int num_entries = 0;
> - unsigned int pages;
> int i, r;
>
> *sgt = kmalloc(sizeof(**sgt), GFP_KERNEL);
> if (!*sgt)
> return -ENOMEM;
>
> - for (pages = mem->num_pages, node = mem->mm_node;
> - pages; pages -= node->size, ++node)
> - ++num_entries;
> + // Determine the number of DRM_MM nodes to export
> + amdgpu_res_first(mem, offset, length, &cursor);
> + while (cursor.remaining) {
> + num_entries++;
> + amdgpu_res_next(&cursor, cursor.size);
> + }
>
> r = sg_alloc_table(*sgt, num_entries, GFP_KERNEL);
> if (r)
> goto error_free;
>
> + // Initialize scatterlist nodes of sg_table
> for_each_sgtable_sg((*sgt), sg, i)
> sg->length = 0;
>
> - node = mem->mm_node;
> + // Walk down DRM_MM nodes to populate scatterlist nodes
> + // @note: Use iterator api to get first the DRM_MM node
> + // and the number of bytes from it. Access the following
> + // DRM_MM node(s) if more buffer needs to exported
Please use C style comments for consistency.
Alex
> + amdgpu_res_first(mem, offset, length, &cursor);
> for_each_sgtable_sg((*sgt), sg, i) {
> - phys_addr_t phys = (node->start << PAGE_SHIFT) +
> - adev->gmc.aper_base;
> - size_t size = node->size << PAGE_SHIFT;
> dma_addr_t addr;
> + size_t size = cursor.size;
> + phys_addr_t phys = cursor.start + adev->gmc.aper_base;
>
> - ++node;
> addr = dma_map_resource(dev, phys, size, dir,
> DMA_ATTR_SKIP_CPU_SYNC);
> r = dma_mapping_error(dev, addr);
> @@ -615,7 +624,10 @@ int amdgpu_vram_mgr_alloc_sgt(struct amdgpu_device *adev,
> sg_set_page(sg, NULL, size, 0);
> sg_dma_address(sg) = addr;
> sg_dma_len(sg) = size;
> +
> + amdgpu_res_next(&cursor, cursor.size);
> }
> +
> return 0;
>
> error_unmap:
> --
> 2.30.0
>
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