@@ -44,7 +44,7 @@ static int uvc_queue_setup(struct vb2_queue *vq,
{
struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
struct uvc_video *video = container_of(queue, struct uvc_video, queue);
- unsigned int req_size;
+ unsigned int req_size, max_req_size;
unsigned int nreq;
if (*nbuffers > UVC_MAX_VIDEO_BUFFERS)
@@ -54,15 +54,29 @@ static int uvc_queue_setup(struct vb2_queue *vq,
sizes[0] = video->imagesize;
- req_size = video->ep->maxpacket
+ nreq = DIV_ROUND_UP(video->interval, video->ep->desc->bInterval * 1250);
+
+ req_size = DIV_ROUND_UP(sizes[0], nreq);
+
+ max_req_size = video->ep->maxpacket
* max_t(unsigned int, video->ep->maxburst, 1)
* (video->ep->mult);
- /* We divide by two, to increase the chance to run
- * into fewer requests for smaller framesizes.
- */
- nreq = DIV_ROUND_UP(DIV_ROUND_UP(sizes[0], 2), req_size);
- nreq = clamp(nreq, 4U, 64U);
+ if (!req_size) {
+ req_size = max_req_size;
+
+ /* We divide by two, to increase the chance to run
+ * into fewer requests for smaller framesizes.
+ */
+ nreq = DIV_ROUND_UP(DIV_ROUND_UP(sizes[0], 2), req_size);
+ nreq = clamp(nreq, 4U, 64U);
+ } else if (req_size > max_req_size) {
+ /* The prepared interval length and expected buffer size
+ * is not possible to stream with the currently configured
+ * isoc bandwidth
+ */
+ return -EINVAL;
+ }
video->req_size = req_size;
video->uvc_num_requests = nreq;
@@ -304,7 +304,7 @@ static int uvcg_video_usb_req_queue(struct uvc_video *video,
*/
if (list_empty(&video->req_free) || ureq->last_buf ||
!(video->req_int_count %
- DIV_ROUND_UP(video->uvc_num_requests, 4))) {
+ clamp(DIV_ROUND_UP(video->uvc_num_requests, 4), 4U, 16U))) {
video->req_int_count = 0;
req->no_interrupt = 0;
} else {
With the information of the interval frame length it is now possible to calculate the number of usb requests by the frame duration. Based on the request size and the imagesize we calculate the actual size per request. This has calculation has the benefit that the frame data is equally distributed over all allocated requests. We keep the current req_size calculation as a fallback, if the interval callbacks did not set the interval property. Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de> --- drivers/usb/gadget/function/uvc_queue.c | 28 +++++++++++++++++++++------- drivers/usb/gadget/function/uvc_video.c | 2 +- 2 files changed, 22 insertions(+), 8 deletions(-)