[PATCH v2] media: v4l2-mem2mem: Apply DST_QUEUE_OFF_BASE on MMAP buffers across ioctls
From: Chen-Yu Tsai
Date: Thu Dec 09 2021 - 11:38:27 EST
DST_QUEUE_OFF_BASE is applied to offset/mem_offset on MMAP capture buffers
only for the VIDIOC_QUERYBUF ioctl, while the userspace fields (including
offset/mem_offset) are filled in for VIDIOC_{QUERY,PREPARE,Q,DQ}BUF
ioctls. This leads to differences in the values presented to userspace.
If userspace attempts to mmap the capture buffer directly using values
from DQBUF, it will fail.
Move the code that applies the magic offset into a helper, and call
that helper from all four ioctl entry points.
Fixes: 7f98639def42 ("V4L/DVB: add memory-to-memory device helper framework for videobuf")
Fixes: 908a0d7c588e ("[media] v4l: mem2mem: port to videobuf2")
Signed-off-by: Chen-Yu Tsai <wenst@xxxxxxxxxxxx>
---
Changes since v1:
- Bail out directly without adjusting offsets if the respective
vb2_*() calls failed
This was tested on RK3399 with
gst-launch-1.0 videotestsrc num-buffers=2 ! v4l2jpegenc ! fakesink
and verifying the values using the V4L2 debug messages:
video2: VIDIOC_QUERYBUF: 00:00:00.000000 index=0, type=vid-cap-mplane, request_fd=0, flags=0x00004000, field=any, sequence=0, memory=mmap
plane 0: bytesused=0, data_offset=0x00000000, offset/userptr=0x40000000, length=2097152
timecode=00:00:00 type=0, flags=0x00000000, frames=0, userbits=0x00000000
video2: VIDIOC_QUERYBUF: 00:00:00.000000 index=0, type=vid-out-mplane, request_fd=0, flags=0x00004000, field=any, sequence=0, memory=mmap
plane 0: bytesused=0, data_offset=0x00000000, offset/userptr=0x0, length=153600
timecode=00:00:00 type=0, flags=0x00000000, frames=0, userbits=0x00000000
video2: VIDIOC_QBUF: 00:00:00.000000 index=0, type=vid-cap-mplane, request_fd=0, flags=0x00004003, field=any, sequence=0, memory=mmap
plane 0: bytesused=2097152, data_offset=0x00000000, offset/userptr=0x40000000, length=2097152
timecode=00:00:00 type=0, flags=0x00000000, frames=0, userbits=0x00000000
video2: VIDIOC_QBUF: 00:00:00.000000 index=0, type=vid-out-mplane, request_fd=0, flags=0x00004003, field=none, sequence=0, memory=mmap
plane 0: bytesused=153600, data_offset=0x00000000, offset/userptr=0x0, length=153600
timecode=00:00:00 type=0, flags=0x00000000, frames=0, userbits=0x00000000
video2: VIDIOC_DQBUF: 00:00:00.000000 index=0, type=vid-cap-mplane, request_fd=0, flags=0x00004001, field=none, sequence=0, memory=mmap
plane 0: bytesused=6324, data_offset=0x00000000, offset/userptr=0x40000000, length=2097152
timecode=00:00:00 type=0, flags=0x00000000, frames=0, userbits=0x00000000
video2: VIDIOC_DQBUF: 00:00:00.000000 index=0, type=vid-out-mplane, request_fd=0, flags=0x00004001, field=none, sequence=0, memory=mmap
plane 0: bytesused=153600, data_offset=0x00000000, offset/userptr=0x0, length=153600
timecode=00:00:00 type=0, flags=0x00000000, frames=0, userbits=0x00000000
Gstreamer doesn't do PREPAREBUF calls, so that path was not verified.
However the code changes are exactly the same, so I'm quite confident
about them.
---
drivers/media/v4l2-core/v4l2-mem2mem.c | 53 ++++++++++++++++++++------
1 file changed, 41 insertions(+), 12 deletions(-)
diff --git a/drivers/media/v4l2-core/v4l2-mem2mem.c b/drivers/media/v4l2-core/v4l2-mem2mem.c
index e2654b422334..3bac9e373502 100644
--- a/drivers/media/v4l2-core/v4l2-mem2mem.c
+++ b/drivers/media/v4l2-core/v4l2-mem2mem.c
@@ -585,19 +585,14 @@ int v4l2_m2m_reqbufs(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
}
EXPORT_SYMBOL_GPL(v4l2_m2m_reqbufs);
-int v4l2_m2m_querybuf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
- struct v4l2_buffer *buf)
+static void v4l2_m2m_adjust_mem_offset(struct vb2_queue *vq,
+ struct v4l2_buffer *buf)
{
- struct vb2_queue *vq;
- int ret = 0;
- unsigned int i;
-
- vq = v4l2_m2m_get_vq(m2m_ctx, buf->type);
- ret = vb2_querybuf(vq, buf);
-
/* Adjust MMAP memory offsets for the CAPTURE queue */
if (buf->memory == V4L2_MEMORY_MMAP && V4L2_TYPE_IS_CAPTURE(vq->type)) {
if (V4L2_TYPE_IS_MULTIPLANAR(vq->type)) {
+ unsigned int i;
+
for (i = 0; i < buf->length; ++i)
buf->m.planes[i].m.mem_offset
+= DST_QUEUE_OFF_BASE;
@@ -605,8 +600,23 @@ int v4l2_m2m_querybuf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
buf->m.offset += DST_QUEUE_OFF_BASE;
}
}
+}
- return ret;
+int v4l2_m2m_querybuf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
+ struct v4l2_buffer *buf)
+{
+ struct vb2_queue *vq;
+ int ret = 0;
+
+ vq = v4l2_m2m_get_vq(m2m_ctx, buf->type);
+ ret = vb2_querybuf(vq, buf);
+ if (ret)
+ return ret;
+
+ /* Adjust MMAP memory offsets for the CAPTURE queue */
+ v4l2_m2m_adjust_mem_offset(vq, buf);
+
+ return 0;
}
EXPORT_SYMBOL_GPL(v4l2_m2m_querybuf);
@@ -763,6 +773,9 @@ int v4l2_m2m_qbuf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
if (ret)
return ret;
+ /* Adjust MMAP memory offsets for the CAPTURE queue */
+ v4l2_m2m_adjust_mem_offset(vq, buf);
+
/*
* If the capture queue is streaming, but streaming hasn't started
* on the device, but was asked to stop, mark the previously queued
@@ -784,9 +797,17 @@ int v4l2_m2m_dqbuf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
struct v4l2_buffer *buf)
{
struct vb2_queue *vq;
+ int ret;
vq = v4l2_m2m_get_vq(m2m_ctx, buf->type);
- return vb2_dqbuf(vq, buf, file->f_flags & O_NONBLOCK);
+ ret = vb2_dqbuf(vq, buf, file->f_flags & O_NONBLOCK);
+ if (ret)
+ return ret;
+
+ /* Adjust MMAP memory offsets for the CAPTURE queue */
+ v4l2_m2m_adjust_mem_offset(vq, buf);
+
+ return 0;
}
EXPORT_SYMBOL_GPL(v4l2_m2m_dqbuf);
@@ -795,9 +816,17 @@ int v4l2_m2m_prepare_buf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
{
struct video_device *vdev = video_devdata(file);
struct vb2_queue *vq;
+ int ret;
vq = v4l2_m2m_get_vq(m2m_ctx, buf->type);
- return vb2_prepare_buf(vq, vdev->v4l2_dev->mdev, buf);
+ ret = vb2_prepare_buf(vq, vdev->v4l2_dev->mdev, buf);
+ if (ret)
+ return ret;
+
+ /* Adjust MMAP memory offsets for the CAPTURE queue */
+ v4l2_m2m_adjust_mem_offset(vq, buf);
+
+ return 0;
}
EXPORT_SYMBOL_GPL(v4l2_m2m_prepare_buf);
--
2.34.1.400.ga245620fadb-goog