linux-kernel - [PATCH v3 09/10] usb: gadget: uvc: set req_length based on payload by nreqs instead of req

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Message-Id: <20240403-uvc_request_length_by_interval-v3-9-4da7033dd488@pengutronix.de>
Date: Sat, 27 Jul 2024 00:02:44 +0200
From: Michael Grzeschik <m.grzeschik@...gutronix.de>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>, 
 Daniel Scally <dan.scally@...asonboard.com>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 Avichal Rakesh <arakesh@...gle.com>
Cc: linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Michael Grzeschik <m.grzeschik@...gutronix.de>
Subject: [PATCH v3 09/10] usb: gadget: uvc: set req_length based on payload
 by nreqs instead of req_size

For uncompressed formats it makes sense to fill the requests with its
maximum since the amount of requests and its size is calculated for
this exact amount. Compressed formats generate content depending amount
of data that is set in the vb2 buffer by the payload_size. When
streaming those formats it is even better to scatter that smaller
data over all requests.

Signed-off-by: Michael Grzeschik <m.grzeschik@...gutronix.de>

---
v1 -> v3: new patch
---
 drivers/usb/gadget/function/uvc_queue.c |  9 ++++++++-
 drivers/usb/gadget/function/uvc_queue.h |  1 +
 drivers/usb/gadget/function/uvc_video.c | 13 ++++++-------
 3 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/drivers/usb/gadget/function/uvc_queue.c b/drivers/usb/gadget/function/uvc_queue.c
index ab04df0e4f360..e33ce72325031 100644
--- a/drivers/usb/gadget/function/uvc_queue.c
+++ b/drivers/usb/gadget/function/uvc_queue.c
@@ -94,6 +94,7 @@ static int uvc_queue_setup(struct vb2_queue *vq,
 static int uvc_buffer_prepare(struct vb2_buffer *vb)
 {
 	struct uvc_video_queue *queue = vb2_get_drv_priv(vb->vb2_queue);
+	struct uvc_video *video = container_of(queue, struct uvc_video, queue);
 	struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
 	struct uvc_buffer *buf = container_of(vbuf, struct uvc_buffer, buf);
 
@@ -116,8 +117,14 @@ static int uvc_buffer_prepare(struct vb2_buffer *vb)
 	buf->length = vb2_plane_size(vb, 0);
 	if (vb->type == V4L2_BUF_TYPE_VIDEO_CAPTURE)
 		buf->bytesused = 0;
-	else
+	else {
+		unsigned int nreq;
+		nreq = DIV_ROUND_UP(video->interval, video->ep->desc->bInterval * 1250);
 		buf->bytesused = vb2_get_plane_payload(vb, 0);
+		buf->req_payload_size =
+			  DIV_ROUND_UP(buf->bytesused +
+					(nreq * UVCG_REQUEST_HEADER_LEN), nreq);
+	}
 
 	return 0;
 }
diff --git a/drivers/usb/gadget/function/uvc_queue.h b/drivers/usb/gadget/function/uvc_queue.h
index 41f87b917f6bc..a7355442dd6cd 100644
--- a/drivers/usb/gadget/function/uvc_queue.h
+++ b/drivers/usb/gadget/function/uvc_queue.h
@@ -39,6 +39,7 @@ struct uvc_buffer {
 	unsigned int offset;
 	unsigned int length;
 	unsigned int bytesused;
+	unsigned int req_payload_size;
 };
 
 #define UVC_QUEUE_DISCONNECTED		(1 << 0)
diff --git a/drivers/usb/gadget/function/uvc_video.c b/drivers/usb/gadget/function/uvc_video.c
index fd2195f7153d9..f6911f124be4b 100644
--- a/drivers/usb/gadget/function/uvc_video.c
+++ b/drivers/usb/gadget/function/uvc_video.c
@@ -136,7 +136,7 @@ uvc_video_encode_isoc_sg(struct usb_request *req, struct uvc_video *video,
 	unsigned int pending = buf->bytesused - video->queue.buf_used;
 	struct uvc_request *ureq = req->context;
 	struct scatterlist *sg, *iter;
-	unsigned int len = video->req_size;
+	unsigned int len = buf->req_payload_size;
 	unsigned int sg_left, part = 0;
 	unsigned int i;
 	int header_len;
@@ -145,16 +145,15 @@ uvc_video_encode_isoc_sg(struct usb_request *req, struct uvc_video *video,
 	sg_init_table(sg, ureq->sgt.nents);
 
 	/* Init the header. */
-	header_len = uvc_video_encode_header(video, buf, ureq->header,
-				      video->req_size);
+	header_len = uvc_video_encode_header(video, buf, ureq->header, len);
 	sg_set_buf(sg, ureq->header, header_len);
 	len -= header_len;
 
 	if (pending <= len)
 		len = pending;
 
-	req->length = (len == pending) ?
-		len + header_len : video->req_size;
+	req->length = (len == pending) ? len + header_len :
+		buf->req_payload_size;
 
 	/* Init the pending sgs with payload */
 	sg = sg_next(sg);
@@ -202,7 +201,7 @@ uvc_video_encode_isoc(struct usb_request *req, struct uvc_video *video,
 {
 	void *mem = req->buf;
 	struct uvc_request *ureq = req->context;
-	int len = video->req_size;
+	int len = buf->req_payload_size;
 	int ret;
 
 	/* Add the header. */
@@ -214,7 +213,7 @@ uvc_video_encode_isoc(struct usb_request *req, struct uvc_video *video,
 	ret = uvc_video_encode_data(video, buf, mem, len);
 	len -= ret;
 
-	req->length = video->req_size - len;
+	req->length = buf->req_payload_size - len;
 
 	if (buf->bytesused == video->queue.buf_used ||
 			video->queue.flags & UVC_QUEUE_DROP_INCOMPLETE) {

-- 
2.39.2