[PATCH 2/5] usb: gadget: uvc: calculate the number of request depending on framesize

[Michael Grzeschik <m.grzeschik@pengutronix.de>]

The current limitation of possible number of requests being handled is
dependent on the gadget speed. It makes more sense to depend on the
typical frame size when calculating the number of requests. This patch
is changing this and is using the previous limits as boundaries for
reasonable minimum and maximum number of requests.

Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
---
 drivers/usb/gadget/function/uvc_queue.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/gadget/function/uvc_queue.c b/drivers/usb/gadget/function/uvc_queue.c
index cfa0ac4adb04d5..2a091cf07981e1 100644
--- a/drivers/usb/gadget/function/uvc_queue.c
+++ b/drivers/usb/gadget/function/uvc_queue.c
@@ -44,7 +44,8 @@ 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);
-	struct usb_composite_dev *cdev = video->uvc->func.config->cdev;
+	unsigned int req_size;
+	unsigned int nreq;
 
 	if (*nbuffers > UVC_MAX_VIDEO_BUFFERS)
 		*nbuffers = UVC_MAX_VIDEO_BUFFERS;
@@ -53,10 +54,14 @@ static int uvc_queue_setup(struct vb2_queue *vq,
 
 	sizes[0] = video->imagesize;
 
-	if (cdev->gadget->speed < USB_SPEED_SUPER)
-		video->uvc_num_requests = 4;
-	else
-		video->uvc_num_requests = 64;
+	req_size = video->ep->maxpacket
+		 * max_t(unsigned int, video->ep->maxburst, 1)
+		 * (video->ep->mult);
+
+	nreq = DIV_ROUND_UP(DIV_ROUND_UP(sizes[0], 2), req_size);
+	nreq = min_t(unsigned int, nreq, 64);
+	nreq = max_t(unsigned int, nreq, 4);
+	video->uvc_num_requests = nreq;
 
 	return 0;
 }
-- 
2.30.2