[PATCH] drm/gem-cma-helper: Change the level of the allocation failure message

[Boris Brezillon]

drm_gem_cma_create() prints an error message when dma_alloc_wc() fails to
allocate the amount of memory we requested. This can lead to annoying
error messages when CMA is only one possible source of memory for the BO
allocation.

Turn this error message into a debug one and add a __must_check specifier
to make sure all callers are checking the return value.

Signed-off-by: Boris Brezillon <boris.brezillon at free-electrons.com>
---
Hello,

This problem happens with the VC4 driver which can flush its internal
cache if case of CMA allocation failures. We should only complain if the
last CMA allocation fails (the one happening after all internal caches
have been flushed).

Regards,

Boris
---
 drivers/gpu/drm/drm_gem_cma_helper.c | 4 ++--
 include/drm/drm_gem_cma_helper.h     | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c
index 373e33f22be4..e96c95c4fd23 100644
--- a/drivers/gpu/drm/drm_gem_cma_helper.c
+++ b/drivers/gpu/drm/drm_gem_cma_helper.c
@@ -95,7 +95,7 @@ __drm_gem_cma_create(struct drm_device *drm, size_t size)
  *
  * Returns:
  * A struct drm_gem_cma_object * on success or an ERR_PTR()-encoded negative
- * error code on failure.
+ * error code on failure. Callers must check the return value.
  */
 struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm,
 					      size_t size)
@@ -112,7 +112,7 @@ struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm,
 	cma_obj->vaddr = dma_alloc_wc(drm->dev, size, &cma_obj->paddr,
 				      GFP_KERNEL | __GFP_NOWARN);
 	if (!cma_obj->vaddr) {
-		dev_err(drm->dev, "failed to allocate buffer with size %zu\n",
+		dev_dbg(drm->dev, "failed to allocate buffer with size %zu\n",
 			size);
 		ret = -ENOMEM;
 		goto error;
diff --git a/include/drm/drm_gem_cma_helper.h b/include/drm/drm_gem_cma_helper.h
index 58a739bf15f1..1b7d938a31a0 100644
--- a/include/drm/drm_gem_cma_helper.h
+++ b/include/drm/drm_gem_cma_helper.h
@@ -77,8 +77,8 @@ int drm_gem_cma_dumb_create(struct drm_file *file_priv,
 int drm_gem_cma_mmap(struct file *filp, struct vm_area_struct *vma);
 
 /* allocate physical memory */
-struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm,
-					      size_t size);
+struct drm_gem_cma_object *
+__must_check drm_gem_cma_create(struct drm_device *drm, size_t size);
 
 extern const struct vm_operations_struct drm_gem_cma_vm_ops;
 
-- 
2.11.0