[PATCH 1/2] drm/ttm: allow zero sized kernel allocations

[PATCH 1/2] drm/ttm: allow zero sized kernel allocations

[Christian König]

From: Christian König <christian.koenig@amd.com>

This patch allows to create zero sized TTM buffer
objects for driver internal use.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/ttm/ttm_bo.c      | 4 ++--
 drivers/gpu/drm/ttm/ttm_bo_util.c | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 3da89d5..0b96a3b 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -309,7 +309,7 @@ static int ttm_bo_handle_move_mem(struct ttm_buffer_object *bo,
 		if (ret)
 			goto out_err;
 
-		if (mem->mem_type != TTM_PL_SYSTEM) {
+		if (bo->ttm->num_pages && mem->mem_type != TTM_PL_SYSTEM) {
 			ret = ttm_tt_bind(bo->ttm, mem);
 			if (ret)
 				goto out_err;
@@ -1107,7 +1107,7 @@ int ttm_bo_init(struct ttm_bo_device *bdev,
 	}
 
 	num_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
-	if (num_pages == 0) {
+	if (type != ttm_bo_type_kernel && num_pages == 0) {
 		pr_err("Illegal buffer object size\n");
 		if (destroy)
 			(*destroy)(bo);
diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
index 30e5d90..8354195 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_util.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
@@ -63,7 +63,7 @@ int ttm_bo_move_ttm(struct ttm_buffer_object *bo,
 	if (unlikely(ret != 0))
 		return ret;
 
-	if (new_mem->mem_type != TTM_PL_SYSTEM) {
+	if (ttm->num_pages && new_mem->mem_type != TTM_PL_SYSTEM) {
 		ret = ttm_tt_bind(ttm, new_mem);
 		if (unlikely(ret != 0))
 			return ret;
-- 
1.9.1

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[PATCH 2/2] drm/radeon: use zero sized BOs for fences v2

[Christian König]

From: Christian König <christian.koenig@amd.com>

This patch allows userspace to created zero sized buffers
for use as pure synchronization object.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/radeon/radeon_drv.c    | 3 ++-
 drivers/gpu/drm/radeon/radeon_object.c | 2 +-
 drivers/gpu/drm/radeon/radeon_vm.c     | 3 +++
 3 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/radeon/radeon_drv.c b/drivers/gpu/drm/radeon/radeon_drv.c
index 86d6b56..5ec6273 100644
--- a/drivers/gpu/drm/radeon/radeon_drv.c
+++ b/drivers/gpu/drm/radeon/radeon_drv.c
@@ -84,9 +84,10 @@
  *   2.39.0 - Add INFO query for number of active CUs
  *   2.40.0 - Add RADEON_GEM_GTT_WC/UC, flush HDP cache before submitting
  *            CS to GPU
+ *   2.41.0 - Allow zero sized BOs
  */
 #define KMS_DRIVER_MAJOR	2
-#define KMS_DRIVER_MINOR	40
+#define KMS_DRIVER_MINOR	41
 #define KMS_DRIVER_PATCHLEVEL	0
 int radeon_driver_load_kms(struct drm_device *dev, unsigned long flags);
 int radeon_driver_unload_kms(struct drm_device *dev);
diff --git a/drivers/gpu/drm/radeon/radeon_object.c b/drivers/gpu/drm/radeon/radeon_object.c
index 480c87d..9dd670e 100644
--- a/drivers/gpu/drm/radeon/radeon_object.c
+++ b/drivers/gpu/drm/radeon/radeon_object.c
@@ -154,7 +154,7 @@ int radeon_bo_create(struct radeon_device *rdev,
 
 	size = ALIGN(size, PAGE_SIZE);
 
-	if (kernel) {
+	if (kernel || size == 0) {
 		type = ttm_bo_type_kernel;
 	} else if (sg) {
 		type = ttm_bo_type_sg;
diff --git a/drivers/gpu/drm/radeon/radeon_vm.c b/drivers/gpu/drm/radeon/radeon_vm.c
index 058f200..b2c336a 100644
--- a/drivers/gpu/drm/radeon/radeon_vm.c
+++ b/drivers/gpu/drm/radeon/radeon_vm.c
@@ -883,6 +883,9 @@ int radeon_vm_bo_update(struct radeon_device *rdev,
 	uint32_t flags;
 	int r;
 
+	if (bo_va->bo && radeon_bo_size(bo_va->bo) == 0)
+		return 0;
+
 	if (!bo_va->it.start) {
 		dev_err(rdev->dev, "bo %p don't has a mapping in vm %p\n",
 			bo_va->bo, vm);
-- 
1.9.1

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