[PATCH 09/10] drm/amdgpu: use the AGP aperture for system memory access

[Christian König]

Start to use the old AGP aperture for system memory access.

Signed-off-by: Christian König <christian.koenig at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c     | 24 +++++++++++++++++++++
 drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h     |  1 +
 drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c |  9 ++++++++
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c     | 21 ++++++++++--------
 4 files changed, 46 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
index eed5352f3136..54d353951e21 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
@@ -79,6 +79,30 @@ uint64_t amdgpu_gmc_pd_addr(struct amdgpu_bo *bo)
 	return pd_addr;
 }
 
+/**
+ * amdgpu_gmc_agp_addr - return the address in the AGP address space
+ *
+ * @tbo: TTM BO which needs the address, must be in GTT domain
+ *
+ * Tries to figure out how to access the BO through the AGP aperture. Returns
+ * AMDGPU_BO_INVALID_OFFSET if that is not possible.
+ */
+uint64_t amdgpu_gmc_agp_addr(struct ttm_buffer_object *tbo)
+{
+	struct amdgpu_device *adev = amdgpu_ttm_adev(tbo->bdev);
+	struct ttm_dma_tt *ttm;
+
+	if (tbo->num_pages != 1 || !tbo->ttm ||
+	    tbo->ttm->caching_state == tt_cached)
+		return AMDGPU_BO_INVALID_OFFSET;
+
+	ttm = container_of(tbo->ttm, struct ttm_dma_tt, ttm);
+	if (ttm->dma_address[0] + PAGE_SIZE >= adev->gmc.agp_size)
+		return AMDGPU_BO_INVALID_OFFSET;
+
+	return adev->gmc.agp_start + ttm->dma_address[0];
+}
+
 /**
  * amdgpu_gmc_vram_location - try to find VRAM location
  *
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
index 163110fe375d..6e8432fd3309 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
@@ -137,6 +137,7 @@ static inline bool amdgpu_gmc_vram_full_visible(struct amdgpu_gmc *gmc)
 void amdgpu_gmc_get_pde_for_bo(struct amdgpu_bo *bo, int level,
 			       uint64_t *addr, uint64_t *flags);
 uint64_t amdgpu_gmc_pd_addr(struct amdgpu_bo *bo);
+uint64_t amdgpu_gmc_agp_addr(struct ttm_buffer_object *tbo);
 void amdgpu_gmc_vram_location(struct amdgpu_device *adev, struct amdgpu_gmc *mc,
 			      u64 base);
 void amdgpu_gmc_gart_location(struct amdgpu_device *adev,
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
index c2539f6821c0..deaea11eb39a 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
@@ -132,6 +132,15 @@ static int amdgpu_gtt_mgr_alloc(struct ttm_mem_type_manager *man,
 	else
 		lpfn = adev->gart.num_cpu_pages;
 
+	if (fpfn == 0 && lpfn == adev->gart.num_cpu_pages) {
+		uint64_t addr = amdgpu_gmc_agp_addr(tbo);
+
+		if (addr != AMDGPU_BO_INVALID_OFFSET) {
+			mem->start = addr >> PAGE_SHIFT;
+			return 0;
+		}
+	}
+
 	mode = DRM_MM_INSERT_BEST;
 	if (place && place->flags & TTM_PL_FLAG_TOPDOWN)
 		mode = DRM_MM_INSERT_HIGH;
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index d9f3201c9e5c..281611f6bcd4 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -1103,15 +1103,18 @@ int amdgpu_ttm_alloc_gart(struct ttm_buffer_object *bo)
 	if (unlikely(r))
 		return r;
 
-	/* compute PTE flags for this buffer object */
-	flags = amdgpu_ttm_tt_pte_flags(adev, bo->ttm, &tmp);
-
-	/* Bind pages */
-	gtt->offset = ((u64)tmp.start << PAGE_SHIFT) - adev->gmc.gart_start;
-	r = amdgpu_ttm_gart_bind(adev, bo, flags);
-	if (unlikely(r)) {
-		ttm_bo_mem_put(bo, &tmp);
-		return r;
+	if (amdgpu_gtt_mgr_has_gart_addr(&tmp)) {
+		/* compute PTE flags for this buffer object */
+		flags = amdgpu_ttm_tt_pte_flags(adev, bo->ttm, &tmp);
+
+		/* Bind pages */
+		gtt->offset = ((u64)tmp.start << PAGE_SHIFT) -
+			adev->gmc.gart_start;
+		r = amdgpu_ttm_gart_bind(adev, bo, flags);
+		if (unlikely(r)) {
+			ttm_bo_mem_put(bo, &tmp);
+			return r;
+		}
 	}
 
 	ttm_bo_mem_put(bo, &bo->mem);
-- 
2.17.1