[PATCH 3/3] media: uvcvideo: Allow userspace to increase the meta buffersize

[Ricardo Ribalda]

Now we have the metadata size hardcoded to 10 KiB, this is a value that
works fine for bulk cameras or frames with no extra metadata. But not
for all usecases.

We have seen some cameras that produce more metadata per frame. Eg:
Frame 1 captured (Bytes: 11154)
Frame 2 captured (Bytes: 11616)
Frame 3 captured (Bytes: 11374)
Frame 4 captured (Bytes: 11132)
Frame 5 captured (Bytes: 11594)
Frame 6 captured (Bytes: 11352)
Frame 7 captured (Bytes: 11110)
Frame 8 captured (Bytes: 11572)
Frame 9 captured (Bytes: 11308)

When this happens, the driver (correctly) marks the metadata as ERROR.

This patch let userspace set bigger buffersize via S_FMT.

Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
---
 drivers/media/usb/uvc/uvc_metadata.c | 9 +++++++--
 drivers/media/usb/uvc/uvc_queue.c    | 2 +-
 drivers/media/usb/uvc/uvcvideo.h     | 3 ++-
 3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_metadata.c b/drivers/media/usb/uvc/uvc_metadata.c
index 0a906ae3f971..9de8aba1229e 100644
--- a/drivers/media/usb/uvc/uvc_metadata.c
+++ b/drivers/media/usb/uvc/uvc_metadata.c
@@ -50,7 +50,7 @@ static int uvc_meta_v4l2_get_format(struct file *file, void *priv,
 		return -EINVAL;
 
 	fmt->dataformat = stream->meta.format;
-	fmt->buffersize = UVC_METADATA_BUF_SIZE;
+	fmt->buffersize = stream->meta.buffersize;
 
 	return 0;
 }
@@ -63,6 +63,7 @@ static int uvc_meta_v4l2_try_format(struct file *file, void *priv,
 	struct uvc_device *dev = stream->dev;
 	struct v4l2_meta_format *fmt = &format->fmt.meta;
 	u32 fmeta = V4L2_META_FMT_UVC;
+	u32 buffersize;
 
 	if (format->type != vfh->vdev->queue->type)
 		return -EINVAL;
@@ -74,10 +75,12 @@ static int uvc_meta_v4l2_try_format(struct file *file, void *priv,
 		}
 	}
 
+	buffersize = max(UVC_METADATA_BUF_MIN_SIZE, fmt->buffersize);
+
 	memset(fmt, 0, sizeof(*fmt));
 
 	fmt->dataformat = fmeta;
-	fmt->buffersize = UVC_METADATA_BUF_SIZE;
+	fmt->buffersize = buffersize;
 
 	return 0;
 }
@@ -103,6 +106,7 @@ static int uvc_meta_v4l2_set_format(struct file *file, void *priv,
 		return -EBUSY;
 
 	stream->meta.format = fmt->dataformat;
+	stream->meta.buffersize = fmt->buffersize;
 
 	return 0;
 }
@@ -229,6 +233,7 @@ int uvc_meta_register(struct uvc_streaming *stream)
 	struct uvc_video_queue *queue = &stream->meta.queue;
 
 	stream->meta.format = V4L2_META_FMT_UVC;
+	stream->meta.buffersize = UVC_METADATA_BUF_MIN_SIZE;
 
 	return uvc_register_video_device(dev, stream, queue,
 					 V4L2_BUF_TYPE_META_CAPTURE,
diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
index 68ed2883edb2..89206f761006 100644
--- a/drivers/media/usb/uvc/uvc_queue.c
+++ b/drivers/media/usb/uvc/uvc_queue.c
@@ -83,7 +83,7 @@ static int uvc_queue_setup(struct vb2_queue *vq,
 
 	switch (vq->type) {
 	case V4L2_BUF_TYPE_META_CAPTURE:
-		size = UVC_METADATA_BUF_SIZE;
+		size = stream->meta.buffersize;
 		break;
 
 	default:
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index 9b4849fda12f..5ba698d2a23d 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -409,7 +409,7 @@ struct uvc_stats_stream {
 	unsigned int max_sof;		/* Maximum STC.SOF value */
 };
 
-#define UVC_METADATA_BUF_SIZE 10240
+#define UVC_METADATA_BUF_MIN_SIZE 10240
 
 /**
  * struct uvc_copy_op: Context structure to schedule asynchronous memcpy
@@ -482,6 +482,7 @@ struct uvc_streaming {
 	struct {
 		struct uvc_video_queue queue;
 		u32 format;
+		u32 buffersize;
 	} meta;
 
 	/* Context data used by the bulk completion handler. */

-- 
2.53.0.473.g4a7958ca14-goog