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Subject: media: videobuf2-core: attach once if multiple planes share the same
dbuf
Author: Yunke Cao <yun...@chromium.org>
Date: Wed Aug 14 11:06:43 2024 +0900
When multiple planes use the same dma buf, each plane will have its own dma
buf attachment and mapping. It is a waste of IOVA space.
This patch adds a dbuf_duplicated boolean in vb2_plane. If a plane's dbuf
is the same as an existing plane, do not create another attachment and
mapping.
Signed-off-by: Yunke Cao <yun...@chromium.org>
Acked-by: Tomasz Figa <tf...@chromium.org>
Signed-off-by: Hans Verkuil <hverkuil-ci...@xs4all.nl>
drivers/media/common/videobuf2/videobuf2-core.c | 30 +++++++++++++++++++++----
include/media/videobuf2-core.h | 3 +++
2 files changed, 29 insertions(+), 4 deletions(-)
---
diff --git a/drivers/media/common/videobuf2/videobuf2-core.c
b/drivers/media/common/videobuf2/videobuf2-core.c
index e6af963307e3..500a4e0c84ab 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -303,10 +303,13 @@ static void __vb2_plane_dmabuf_put(struct vb2_buffer *vb,
struct vb2_plane *p)
if (!p->mem_priv)
return;
- if (p->dbuf_mapped)
- call_void_memop(vb, unmap_dmabuf, p->mem_priv);
+ if (!p->dbuf_duplicated) {
+ if (p->dbuf_mapped)
+ call_void_memop(vb, unmap_dmabuf, p->mem_priv);
+
+ call_void_memop(vb, detach_dmabuf, p->mem_priv);
+ }
- call_void_memop(vb, detach_dmabuf, p->mem_priv);
dma_buf_put(p->dbuf);
p->mem_priv = NULL;
p->dbuf = NULL;
@@ -315,6 +318,7 @@ static void __vb2_plane_dmabuf_put(struct vb2_buffer *vb,
struct vb2_plane *p)
p->length = 0;
p->m.fd = 0;
p->data_offset = 0;
+ p->dbuf_duplicated = false;
}
/*
@@ -1379,7 +1383,7 @@ static int __prepare_dmabuf(struct vb2_buffer *vb)
struct vb2_plane planes[VB2_MAX_PLANES];
struct vb2_queue *q = vb->vb2_queue;
void *mem_priv;
- unsigned int plane;
+ unsigned int plane, i;
int ret = 0;
bool reacquired = vb->planes[0].mem_priv == NULL;
@@ -1432,6 +1436,24 @@ static int __prepare_dmabuf(struct vb2_buffer *vb)
}
for (plane = 0; plane < vb->num_planes; ++plane) {
+ /*
+ * This is an optimization to reduce dma_buf
attachment/mapping.
+ * When the same dma_buf is used for multiple planes,
there is no need
+ * to create duplicated attachments.
+ */
+ for (i = 0; i < plane; ++i) {
+ if (planes[plane].dbuf == vb->planes[i].dbuf &&
+ q->alloc_devs[plane] == q->alloc_devs[i]) {
+ vb->planes[plane].dbuf_duplicated =
true;
+ vb->planes[plane].dbuf =
vb->planes[i].dbuf;
+ vb->planes[plane].mem_priv =
vb->planes[i].mem_priv;
+ break;
+ }
+ }
+
+ if (vb->planes[plane].dbuf_duplicated)
+ continue;
+
/* Acquire each plane's memory */
mem_priv = call_ptr_memop(attach_dmabuf,
vb,
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index 955237ac503d..9b02aeba4108 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -154,6 +154,8 @@ struct vb2_mem_ops {
* @mem_priv: private data with this plane.
* @dbuf: dma_buf - shared buffer object.
* @dbuf_mapped: flag to show whether dbuf is mapped or not
+ * @dbuf_duplicated: boolean to show whether dbuf is duplicated with a
+ * previous plane of the buffer.
* @bytesused: number of bytes occupied by data in the plane (payload).
* @length: size of this plane (NOT the payload) in bytes. The maximum
* valid size is MAX_UINT - PAGE_SIZE.
@@ -179,6 +181,7 @@ struct vb2_plane {
void *mem_priv;
struct dma_buf *dbuf;
unsigned int dbuf_mapped;
+ bool dbuf_duplicated;
unsigned int bytesused;
unsigned int length;
unsigned int min_length;
