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UPSTREAM: usb: gadget: uvc: clean up comments and styling in video_pump

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This patch elaborates on some of the edge cases handled by
video_pump around setting no_interrupt flag, and brings the
code style in line with rest of the file.

Link: https://lore.kernel.org/20230602151916.GH26944@pendragon.ideasonboard.com/
Signed-off-by: Avichal Rakesh <arakesh@google.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Message-ID: <20230602220455.313801-1-arakesh@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Bug: 301887900
Change-Id: Ie5f28e8d8f55158e32e0ff03b79f0f18cce7d6af
(cherry picked from commit 5ae8a35459
 https://kernel.googlesource.com/pub/scm/linux/kernel/git/gregkh/usb usb-next)
Signed-off-by: Avichal Rakesh <arakesh@google.com>
This commit is contained in:
Avichal Rakesh
2023-06-02 15:04:55 -07:00
committed by Todd Kjos
parent 82fe654f56
commit defd93f219
1 changed files with 25 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files

38
drivers/usb/gadget/function/uvc_video.c
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@@ -382,13 +382,13 @@ static void uvcg_video_pump(struct work_struct *work)
{ {
struct uvc_video *video = container_of(work, struct uvc_video, pump); struct uvc_video *video = container_of(work, struct uvc_video, pump);
struct uvc_video_queue *queue = &video->queue; struct uvc_video_queue *queue = &video->queue;
/* video->max_payload_size is only set when using bulk transfer */
bool is_bulk = video->max_payload_size;
struct usb_request *req = NULL; struct usb_request *req = NULL;
struct uvc_buffer *buf; struct uvc_buffer *buf;
unsigned long flags; unsigned long flags;
bool buf_done;
int ret; int ret;
bool buf_int;
/* video->max_payload_size is only set when using bulk transfer */
bool is_bulk = video->max_payload_size;
while (video->ep->enabled) { while (video->ep->enabled) {
/* /*
@@ -414,20 +414,19 @@ static void uvcg_video_pump(struct work_struct *work)
if (buf != NULL) { if (buf != NULL) {
video->encode(req, video, buf); video->encode(req, video, buf);
/* Always interrupt for the last request of a video buffer */ buf_done = buf->state == UVC_BUF_STATE_DONE;
buf_int = buf->state == UVC_BUF_STATE_DONE;
} else if (!(queue->flags & UVC_QUEUE_DISCONNECTED) && !is_bulk) { } else if (!(queue->flags & UVC_QUEUE_DISCONNECTED) && !is_bulk) {
/* /*
* No video buffer available; the queue is still connected and * No video buffer available; the queue is still connected and
* we're traferring over ISOC. Queue a 0 length request to * we're transferring over ISOC. Queue a 0 length request to
* prevent missed ISOC transfers. * prevent missed ISOC transfers.
*/ */
req->length = 0; req->length = 0;
buf_int = false; buf_done = false;
} else { } else {
/* /*
* Either queue has been disconnected or no video buffer * Either the queue has been disconnected or no video buffer
* available to bulk transfer. Either way, stop processing * available for bulk transfer. Either way, stop processing
* further. * further.
*/ */
spin_unlock_irqrestore(&queue->irqlock, flags); spin_unlock_irqrestore(&queue->irqlock, flags);
@@ -435,11 +434,24 @@ static void uvcg_video_pump(struct work_struct *work)
} }
/* /*
* With usb3 we have more requests. This will decrease the * With USB3 handling more requests at a higher speed, we can't
* interrupt load to a quarter but also catches the corner * afford to generate an interrupt for every request. Decide to
* cases, which needs to be handled. * interrupt:
*
* - When no more requests are available in the free queue, as
* this may be our last chance to refill the endpoint's
* request queue.
*
* - When this is request is the last request for the video
* buffer, as we want to start sending the next video buffer
* ASAP in case it doesn't get started already in the next
* iteration of this loop.
*
* - Four times over the length of the requests queue (as
* indicated by video->uvc_num_requests), as a trade-off
* between latency and interrupt load.
*/ */
if (list_empty(&video->req_free) || buf_int || if (list_empty(&video->req_free) || buf_done ||
!(video->req_int_count % !(video->req_int_count %
DIV_ROUND_UP(video->uvc_num_requests, 4))) { DIV_ROUND_UP(video->uvc_num_requests, 4))) {
video->req_int_count = 0; video->req_int_count = 0;