Thread (133 messages) 133 messages, 6 authors, 2023-11-10

Re: [PATCH v14 53/56] media: core: Free range of buffers

From: Tomasz Figa <tfiga@chromium.org>
Date: 2023-11-09 09:10:28
Also in: linux-arm-msm, linux-media, linux-mediatek, linux-rockchip, linux-staging, lkml

On Tue, Oct 31, 2023 at 05:31:01PM +0100, Benjamin Gaignard wrote:
quoted hunk ↗ jump to hunk
Improve __vb2_queue_free() and __vb2_free_mem() to free
range of buffers and not only the last few buffers.
Intoduce starting index to be flexible on range and change the loops
according to this parameters.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
---
 .../media/common/videobuf2/videobuf2-core.c   | 59 +++++++++----------
 1 file changed, 28 insertions(+), 31 deletions(-)
diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index 6e88406fcae9..010a8bca0240 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -519,15 +519,13 @@ static int __vb2_queue_alloc(struct vb2_queue *q, enum vb2_memory memory,
 /*
  * __vb2_free_mem() - release all video buffer memory for a given queue
This comment is kind of outdated. Maybe we should replace it with

	release video buffer memory for a given range of buffers in a given
	queue

?
  */
-static void __vb2_free_mem(struct vb2_queue *q, unsigned int buffers)
+static void __vb2_free_mem(struct vb2_queue *q, unsigned int start, unsigned int count)
 {
-	unsigned int buffer;
+	unsigned int i;
 	struct vb2_buffer *vb;
-	unsigned int q_num_buffers = vb2_get_num_buffers(q);
 
-	for (buffer = q_num_buffers - buffers; buffer < q_num_buffers;
-	     ++buffer) {
-		vb = vb2_get_buffer(q, buffer);
+	for (i = start; i < q->max_num_buffers && i < start + count; i++) {
We could make this (and all those numerous simialr iterations) more
efficient by using bitmap helpers (probably wrapped in some vb2 helpers),
e.g. for_each_set_bit_from() (vb2_for_each_buffer_from()?). It can be done
in a follow up patch separately from this series though.
quoted hunk ↗ jump to hunk
+		vb = vb2_get_buffer(q, i);
 		if (!vb)
 			continue;
 
@@ -542,35 +540,35 @@ static void __vb2_free_mem(struct vb2_queue *q, unsigned int buffers)
 }
 
 /*
- * __vb2_queue_free() - free buffers at the end of the queue - video memory and
+ * __vb2_queue_free() - free count buffers from start index of the queue - video memory and
nit: How about using the @count and @start notation to refer the argument
names? (Can be done with a follow up patch outside of this series later.)
  * related information, if no buffers are left return the queue to an
  * uninitialized state. Might be called even if the queue has already been freed.
  */
-static void __vb2_queue_free(struct vb2_queue *q, unsigned int buffers)
+static void __vb2_queue_free(struct vb2_queue *q, unsigned int start, unsigned int count)
 {
-	unsigned int buffer;
-	unsigned int q_num_buffers = vb2_get_num_buffers(q);
+	unsigned int i;
 
 	lockdep_assert_held(&q->mmap_lock);
 
 	/* Call driver-provided cleanup function for each buffer, if provided */
-	for (buffer = q_num_buffers - buffers; buffer < q_num_buffers;
-	     ++buffer) {
-		struct vb2_buffer *vb = vb2_get_buffer(q, buffer);
+	for (i = start; i < q->max_num_buffers && i < start + count; i++) {
+		struct vb2_buffer *vb = vb2_get_buffer(q, i);
 
-		if (vb && vb->planes[0].mem_priv)
+		if (!vb)
+			continue;
+		if (vb->planes[0].mem_priv)
nit: Not sure if we really had to change this, but I'm fine with either.

Best regards,
Tomasz

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