dma-buf: Remove range-based flush

This patch removes range-based information used for optimizations in
begin_cpu_access and end_cpu_access.

We don't have any user nor implementation using range-based flush. It seems a
consensus that if we ever want something like that again (or even more robust
using 2D, 3D sub-range regions) we can use the upcoming dma-buf sync ioctl for
such.

Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Tiago Vignatti <tiago.vignatti@intel.com>
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1450820214-12509-3-git-send-email-tiago.vignatti@intel.com

Documentation/dma-buf-sharing.txt

@@ -257,17 +257,15 @@ Access to a dma_buf from the kernel context involves three steps:
 
    Interface:
       int dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
-				   size_t start, size_t len,
 				   enum dma_data_direction direction)
 
    This allows the exporter to ensure that the memory is actually available for
    cpu access - the exporter might need to allocate or swap-in and pin the
    backing storage. The exporter also needs to ensure that cpu access is
-   coherent for the given range and access direction. The range and access
+   coherent for the access direction. The direction can be used by the exporter
-   direction can be used by the exporter to optimize the cache flushing, i.e.
+   to optimize the cache flushing, i.e. access with a different direction (read
-   access outside of the range or with a different direction (read instead of
+   instead of write) might return stale or even bogus data (e.g. when the
-   write) might return stale or even bogus data (e.g. when the exporter needs to
+   exporter needs to copy the data to temporary storage).
-   copy the data to temporary storage).
 
    This step might fail, e.g. in oom conditions.
 
@@ -322,14 +320,13 @@ Access to a dma_buf from the kernel context involves three steps:
 
 3. Finish access
 
-   When the importer is done accessing the range specified in begin_cpu_access,
+   When the importer is done accessing the CPU, it needs to announce this to
-   it needs to announce this to the exporter (to facilitate cache flushing and
+   the exporter (to facilitate cache flushing and unpinning of any pinned
-   unpinning of any pinned resources). The result of any dma_buf kmap calls
+   resources). The result of any dma_buf kmap calls after end_cpu_access is
-   after end_cpu_access is undefined.
+   undefined.
 
    Interface:
       void dma_buf_end_cpu_access(struct dma_buf *dma_buf,
-				  size_t start, size_t len,
 				  enum dma_data_direction dir);
 
 

drivers/dma-buf/dma-buf.c

@@ -539,13 +539,11 @@ EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);
  * preparations. Coherency is only guaranteed in the specified range for the
  * specified access direction.
  * @dmabuf:	[in]	buffer to prepare cpu access for.
- * @start:	[in]	start of range for cpu access.
- * @len:	[in]	length of range for cpu access.
  * @direction:	[in]	length of range for cpu access.
  *
  * Can return negative error values, returns 0 on success.
  */
-int dma_buf_begin_cpu_access(struct dma_buf *dmabuf, size_t start, size_t len,
+int dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
 			     enum dma_data_direction direction)
 {
 	int ret = 0;
@@ -554,8 +552,7 @@ int dma_buf_begin_cpu_access(struct dma_buf *dmabuf, size_t start, size_t len,
 		return -EINVAL;
 
 	if (dmabuf->ops->begin_cpu_access)
-		ret = dmabuf->ops->begin_cpu_access(dmabuf, start,
+		ret = dmabuf->ops->begin_cpu_access(dmabuf, direction);
-							len, direction);
 
 	return ret;
 }
@@ -567,19 +564,17 @@ EXPORT_SYMBOL_GPL(dma_buf_begin_cpu_access);
  * actions. Coherency is only guaranteed in the specified range for the
  * specified access direction.
  * @dmabuf:	[in]	buffer to complete cpu access for.
- * @start:	[in]	start of range for cpu access.
- * @len:	[in]	length of range for cpu access.
  * @direction:	[in]	length of range for cpu access.
  *
  * This call must always succeed.
  */
-void dma_buf_end_cpu_access(struct dma_buf *dmabuf, size_t start, size_t len,
+void dma_buf_end_cpu_access(struct dma_buf *dmabuf,
 			    enum dma_data_direction direction)
 {
 	WARN_ON(!dmabuf);
 
 	if (dmabuf->ops->end_cpu_access)
-		dmabuf->ops->end_cpu_access(dmabuf, start, len, direction);
+		dmabuf->ops->end_cpu_access(dmabuf, direction);
 }
 EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access);
 

drivers/gpu/drm/i915/i915_gem_dmabuf.c

@@ -196,7 +196,7 @@ static int i915_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *
 	return -EINVAL;
 }
 
-static int i915_gem_begin_cpu_access(struct dma_buf *dma_buf, size_t start, size_t length, enum dma_data_direction direction)
+static int i915_gem_begin_cpu_access(struct dma_buf *dma_buf, enum dma_data_direction direction)
 {
 	struct drm_i915_gem_object *obj = dma_buf_to_obj(dma_buf);
 	struct drm_device *dev = obj->base.dev;

drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c

@@ -79,7 +79,7 @@ static void omap_gem_dmabuf_release(struct dma_buf *buffer)
 
 
 static int omap_gem_dmabuf_begin_cpu_access(struct dma_buf *buffer,
-		size_t start, size_t len, enum dma_data_direction dir)
+		enum dma_data_direction dir)
 {
 	struct drm_gem_object *obj = buffer->priv;
 	struct page **pages;
@@ -94,7 +94,7 @@ static int omap_gem_dmabuf_begin_cpu_access(struct dma_buf *buffer,
 }
 
 static void omap_gem_dmabuf_end_cpu_access(struct dma_buf *buffer,
-		size_t start, size_t len, enum dma_data_direction dir)
+		enum dma_data_direction dir)
 {
 	struct drm_gem_object *obj = buffer->priv;
 	omap_gem_put_pages(obj);

drivers/gpu/drm/udl/udl_fb.c

@@ -409,7 +409,6 @@ static int udl_user_framebuffer_dirty(struct drm_framebuffer *fb,
 
 	if (ufb->obj->base.import_attach) {
 		ret = dma_buf_begin_cpu_access(ufb->obj->base.import_attach->dmabuf,
-					       0, ufb->obj->base.size,
 					       DMA_FROM_DEVICE);
 		if (ret)
 			goto unlock;
@@ -425,7 +424,6 @@ static int udl_user_framebuffer_dirty(struct drm_framebuffer *fb,
 
 	if (ufb->obj->base.import_attach) {
 		dma_buf_end_cpu_access(ufb->obj->base.import_attach->dmabuf,
-				       0, ufb->obj->base.size,
 				       DMA_FROM_DEVICE);
 	}
 

drivers/staging/android/ion/ion.c

@@ -1057,8 +1057,7 @@ static void ion_dma_buf_kunmap(struct dma_buf *dmabuf, unsigned long offset,
 {
 }
 
-static int ion_dma_buf_begin_cpu_access(struct dma_buf *dmabuf, size_t start,
+static int ion_dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
-					size_t len,
 					enum dma_data_direction direction)
 {
 	struct ion_buffer *buffer = dmabuf->priv;
@@ -1076,8 +1075,7 @@ static int ion_dma_buf_begin_cpu_access(struct dma_buf *dmabuf, size_t start,
 	return PTR_ERR_OR_ZERO(vaddr);
 }
 
-static void ion_dma_buf_end_cpu_access(struct dma_buf *dmabuf, size_t start,
+static void ion_dma_buf_end_cpu_access(struct dma_buf *dmabuf,
-				       size_t len,
 				       enum dma_data_direction direction)
 {
 	struct ion_buffer *buffer = dmabuf->priv;

drivers/staging/android/ion/ion_test.c

@@ -109,7 +109,7 @@ static int ion_handle_test_kernel(struct dma_buf *dma_buf, void __user *ptr,
 	if (offset > dma_buf->size || size > dma_buf->size - offset)
 		return -EINVAL;
 
-	ret = dma_buf_begin_cpu_access(dma_buf, offset, size, dir);
+	ret = dma_buf_begin_cpu_access(dma_buf, dir);
 	if (ret)
 		return ret;
 
@@ -139,7 +139,7 @@ static int ion_handle_test_kernel(struct dma_buf *dma_buf, void __user *ptr,
 		copy_offset = 0;
 	}
 err:
-	dma_buf_end_cpu_access(dma_buf, offset, size, dir);
+	dma_buf_end_cpu_access(dma_buf, dir);
 	return ret;
 }
 

include/linux/dma-buf.h

@@ -54,7 +54,7 @@ struct dma_buf_attachment;
  * @release: release this buffer; to be called after the last dma_buf_put.
  * @begin_cpu_access: [optional] called before cpu access to invalidate cpu
  * 		      caches and allocate backing storage (if not yet done)
- * 		      respectively pin the objet into memory.
+ * 		      respectively pin the object into memory.
  * @end_cpu_access: [optional] called after cpu access to flush caches.
  * @kmap_atomic: maps a page from the buffer into kernel address
  * 		 space, users may not block until the subsequent unmap call.
@@ -93,10 +93,8 @@ struct dma_buf_ops {
 	/* after final dma_buf_put() */
 	void (*release)(struct dma_buf *);
 
-	int (*begin_cpu_access)(struct dma_buf *, size_t, size_t,
+	int (*begin_cpu_access)(struct dma_buf *, enum dma_data_direction);
-				enum dma_data_direction);
+	void (*end_cpu_access)(struct dma_buf *, enum dma_data_direction);
-	void (*end_cpu_access)(struct dma_buf *, size_t, size_t,
-			       enum dma_data_direction);
 	void *(*kmap_atomic)(struct dma_buf *, unsigned long);
 	void (*kunmap_atomic)(struct dma_buf *, unsigned long, void *);
 	void *(*kmap)(struct dma_buf *, unsigned long);
@@ -224,9 +222,9 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *,
 					enum dma_data_direction);
 void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *,
 				enum dma_data_direction);
-int dma_buf_begin_cpu_access(struct dma_buf *dma_buf, size_t start, size_t len,
+int dma_buf_begin_cpu_access(struct dma_buf *dma_buf,
 			     enum dma_data_direction dir);
-void dma_buf_end_cpu_access(struct dma_buf *dma_buf, size_t start, size_t len,
+void dma_buf_end_cpu_access(struct dma_buf *dma_buf,
 			    enum dma_data_direction dir);
 void *dma_buf_kmap_atomic(struct dma_buf *, unsigned long);
 void dma_buf_kunmap_atomic(struct dma_buf *, unsigned long, void *);