Re: [PATCH 2/2] drm/amdgpu: Add address alignment support to DCC buffers

Christian König <christian.koenig@xxxxxxx> · Thu, 4 Jul 2024 10:47:46 +0200

Am 04.07.24 um 10:30 schrieb Arunpravin Paneer Selvam:
Add address alignment support to the DCC VRAM buffers.

v2:
   - adjust size based on the max_texture_channel_caches values
     only for GFX12 DCC buffers.
   - used AMDGPU_GEM_CREATE_GFX12_DCC flag to apply change only
     for DCC buffers.
   - roundup non power of two DCC buffer adjusted size to nearest
     power of two number as the buddy allocator does not support non
     power of two alignments. This applies only to the contiguous
     DCC buffers.

v3:(Alex)
   - rewrite the max texture channel caches comparison code in an
     algorithmic way to determine the alignment size.

v4:(Alex)
   - Move the logic from amdgpu_vram_mgr_dcc_alignment() to gmc_v12_0.c
     and add a new gmc func callback for dcc alignment. If the callback
     is non-NULL, call it to get the alignment, otherwise, use the default.

v5:(Alex)
   - Set the Alignment to a default value if the callback doesn't exist.
   - Add the callback to amdgpu_gmc_funcs.

Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@xxxxxxx>

Acked-by: Christian König <christian.koenig@xxxxxxx> for the series.

---
  drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h      |  3 ++
  drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 36 ++++++++++++++++++--
  drivers/gpu/drm/amd/amdgpu/gmc_v12_0.c       | 15 ++++++++
  3 files changed, 52 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
index febca3130497..49dfcf112ac1 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
@@ -156,6 +156,8 @@ struct amdgpu_gmc_funcs {
  				      uint64_t addr, uint64_t *flags);
  	/* get the amount of memory used by the vbios for pre-OS console */
  	unsigned int (*get_vbios_fb_size)(struct amdgpu_device *adev);
+	/* get the DCC buffer alignment */
+	u64 (*get_dcc_alignment)(struct amdgpu_device *adev);
  
  	enum amdgpu_memory_partition (*query_mem_partition_mode)(
  		struct amdgpu_device *adev);
@@ -363,6 +365,7 @@ struct amdgpu_gmc {
  	(adev)->gmc.gmc_funcs->override_vm_pte_flags			\
  		((adev), (vm), (addr), (pte_flags))
  #define amdgpu_gmc_get_vbios_fb_size(adev) (adev)->gmc.gmc_funcs->get_vbios_fb_size((adev))
+#define amdgpu_gmc_get_dcc_alignment(adev) ((adev)->gmc.gmc_funcs->get_dcc_alignment((adev)))
  
  /**
   * amdgpu_gmc_vram_full_visible - Check if full VRAM is visible through the BAR
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
index eb94f943b28e..756d1c8cbffd 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
@@ -509,6 +509,16 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
  		vres->flags |= DRM_BUDDY_RANGE_ALLOCATION;
  
  	remaining_size = (u64)vres->base.size;
+	if (bo->flags & AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS &&
+	    bo->flags & AMDGPU_GEM_CREATE_GFX12_DCC) {
+		u64 adjust_size;
+
+		if (adev->gmc.gmc_funcs->get_dcc_alignment) {
+			adjust_size = amdgpu_gmc_get_dcc_alignment(adev);
+			remaining_size = roundup_pow_of_two(remaining_size + adjust_size);
+			vres->flags |= DRM_BUDDY_TRIM_DISABLE;
+		}
+	}
  
  	mutex_lock(&mgr->lock);
  	while (remaining_size) {
@@ -518,8 +528,12 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
  			min_block_size = mgr->default_page_size;
  
  		size = remaining_size;
-		if ((size >= (u64)pages_per_block << PAGE_SHIFT) &&
-		    !(size & (((u64)pages_per_block << PAGE_SHIFT) - 1)))
+
+		if (bo->flags & AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS &&
+		    bo->flags & AMDGPU_GEM_CREATE_GFX12_DCC)
+			min_block_size = size;
+		else if ((size >= (u64)pages_per_block << PAGE_SHIFT) &&
+			 !(size & (((u64)pages_per_block << PAGE_SHIFT) - 1)))
  			min_block_size = (u64)pages_per_block << PAGE_SHIFT;
  
  		BUG_ON(min_block_size < mm->chunk_size);
@@ -550,6 +564,24 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
  	}
  	mutex_unlock(&mgr->lock);
  
+	if (bo->flags & AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS &&
+	    bo->flags & AMDGPU_GEM_CREATE_GFX12_DCC) {
+		struct drm_buddy_block *dcc_block;
+		u64 dcc_start, alignment;
+
+		dcc_block = amdgpu_vram_mgr_first_block(&vres->blocks);
+		dcc_start = amdgpu_vram_mgr_block_start(dcc_block);
+
+		if (adev->gmc.gmc_funcs->get_dcc_alignment) {
+			alignment = amdgpu_gmc_get_dcc_alignment(adev);
+			/* Adjust the start address for DCC buffers only */
+			dcc_start = roundup(dcc_start, alignment);
+			drm_buddy_block_trim(mm, &dcc_start,
+					     (u64)vres->base.size,
+					     &vres->blocks);
+		}
+	}
+
  	vres->base.start = 0;
  	size = max_t(u64, amdgpu_vram_mgr_blocks_size(&vres->blocks),
  		     vres->base.size);
diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v12_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v12_0.c
index fd3ac483760e..4259edcdec8a 100644
--- a/drivers/gpu/drm/amd/amdgpu/gmc_v12_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gmc_v12_0.c
@@ -542,6 +542,20 @@ static unsigned gmc_v12_0_get_vbios_fb_size(struct amdgpu_device *adev)
  	return 0;
  }
  
+static u64 gmc_v12_0_get_dcc_alignment(struct amdgpu_device *adev)
+{
+	u64 max_tex_channel_caches, alignment;
+
+	max_tex_channel_caches = adev->gfx.config.max_texture_channel_caches;
+	if (is_power_of_2(max_tex_channel_caches))
+		alignment = (max_tex_channel_caches / SZ_4) * max_tex_channel_caches;
+	else
+		alignment = roundup_pow_of_two(max_tex_channel_caches) *
+				max_tex_channel_caches;
+
+	return (u64)alignment * SZ_1K;
+}
+
  static const struct amdgpu_gmc_funcs gmc_v12_0_gmc_funcs = {
  	.flush_gpu_tlb = gmc_v12_0_flush_gpu_tlb,
  	.flush_gpu_tlb_pasid = gmc_v12_0_flush_gpu_tlb_pasid,
@@ -551,6 +565,7 @@ static const struct amdgpu_gmc_funcs gmc_v12_0_gmc_funcs = {
  	.get_vm_pde = gmc_v12_0_get_vm_pde,
  	.get_vm_pte = gmc_v12_0_get_vm_pte,
  	.get_vbios_fb_size = gmc_v12_0_get_vbios_fb_size,
+	.get_dcc_alignment = gmc_v12_0_get_dcc_alignment,
  };
  
  static void gmc_v12_0_set_gmc_funcs(struct amdgpu_device *adev)







