diff --git a/drivers/usb/gadget/function/uvc.h b/drivers/usb/gadget/function/uvc.h index be0d012aa244..cb35687b11e7 100644 --- a/drivers/usb/gadget/function/uvc.h +++ b/drivers/usb/gadget/function/uvc.h @@ -105,7 +105,15 @@ struct uvc_video { bool is_enabled; /* tracks whether video stream is enabled */ unsigned int req_size; struct list_head ureqs; /* all uvc_requests allocated by uvc_video */ + + /* USB requests that the video pump thread can encode into */ struct list_head req_free; + + /* + * USB requests video pump thread has already encoded into. These are + * ready to be queued to the endpoint. + */ + struct list_head req_ready; spinlock_t req_lock; unsigned int req_int_count; diff --git a/drivers/usb/gadget/function/uvc_video.c b/drivers/usb/gadget/function/uvc_video.c index 164bdeb7f2a9..98ba524c27f5 100644 --- a/drivers/usb/gadget/function/uvc_video.c +++ b/drivers/usb/gadget/function/uvc_video.c @@ -269,6 +269,101 @@ static int uvcg_video_ep_queue(struct uvc_video *video, struct usb_request *req) return ret; } +/* This function must be called with video->req_lock held. */ +static int uvcg_video_usb_req_queue(struct uvc_video *video, + struct usb_request *req, bool queue_to_ep) +{ + bool is_bulk = video->max_payload_size; + struct list_head *list = NULL; + + if (!video->is_enabled) { + uvc_video_free_request(req->context, video->ep); + return -ENODEV; + } + if (queue_to_ep) { + struct uvc_request *ureq = req->context; + /* + * With USB3 handling more requests at a higher speed, we can't + * afford to generate an interrupt for every request. Decide to + * 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) || ureq->last_buf || + !(video->req_int_count % + DIV_ROUND_UP(video->uvc_num_requests, 4))) { + video->req_int_count = 0; + req->no_interrupt = 0; + } else { + req->no_interrupt = 1; + } + video->req_int_count++; + return uvcg_video_ep_queue(video, req); + } + /* + * If we're not queuing to the ep, for isoc we're queuing + * to the req_ready list, otherwise req_free. + */ + list = is_bulk ? &video->req_free : &video->req_ready; + list_add_tail(&req->list, list); + return 0; +} + +/* + * Must only be called from uvcg_video_enable - since after that we only want to + * queue requests to the endpoint from the uvc_video_complete complete handler. + * This function is needed in order to 'kick start' the flow of requests from + * gadget driver to the usb controller. + */ +static void uvc_video_ep_queue_initial_requests(struct uvc_video *video) +{ + struct usb_request *req = NULL; + unsigned long flags = 0; + unsigned int count = 0; + int ret = 0; + + /* + * We only queue half of the free list since we still want to have + * some free usb_requests in the free list for the video_pump async_wq + * thread to encode uvc buffers into. Otherwise we could get into a + * situation where the free list does not have any usb requests to + * encode into - we always end up queueing 0 length requests to the + * end point. + */ + unsigned int half_list_size = video->uvc_num_requests / 2; + + spin_lock_irqsave(&video->req_lock, flags); + /* + * Take these requests off the free list and queue them all to the + * endpoint. Since we queue 0 length requests with the req_lock held, + * there isn't any 'data' race involved here with the complete handler. + */ + while (count < half_list_size) { + req = list_first_entry(&video->req_free, struct usb_request, + list); + list_del(&req->list); + req->length = 0; + ret = uvcg_video_ep_queue(video, req); + if (ret < 0) { + uvcg_queue_cancel(&video->queue, 0); + break; + } + count++; + } + spin_unlock_irqrestore(&video->req_lock, flags); +} + static void uvc_video_complete(struct usb_ep *ep, struct usb_request *req) { @@ -277,6 +372,8 @@ uvc_video_complete(struct usb_ep *ep, struct usb_request *req) struct uvc_video_queue *queue = &video->queue; struct uvc_buffer *last_buf; unsigned long flags; + bool is_bulk = video->max_payload_size; + int ret = 0; spin_lock_irqsave(&video->req_lock, flags); if (!video->is_enabled) { @@ -330,8 +427,45 @@ uvc_video_complete(struct usb_ep *ep, struct usb_request *req) * back to req_free */ if (video->is_enabled) { - list_add_tail(&req->list, &video->req_free); - queue_work(video->async_wq, &video->pump); + /* + * Here we check whether any request is available in the ready + * list. If it is, queue it to the ep and add the current + * usb_request to the req_free list - for video_pump to fill in. + * Otherwise, just use the current usb_request to queue a 0 + * length request to the ep. Since we always add to the req_free + * list if we dequeue from the ready list, there will never + * be a situation where the req_free list is completely out of + * requests and cannot recover. + */ + struct usb_request *to_queue = req; + + to_queue->length = 0; + if (!list_empty(&video->req_ready)) { + to_queue = list_first_entry(&video->req_ready, + struct usb_request, list); + list_del(&to_queue->list); + list_add_tail(&req->list, &video->req_free); + /* + * Queue work to the wq as well since it is possible that a + * buffer may not have been completely encoded with the set of + * in-flight usb requests for whih the complete callbacks are + * firing. + * In that case, if we do not queue work to the worker thread, + * the buffer will never be marked as complete - and therefore + * not be returned to userpsace. As a result, + * dequeue -> queue -> dequeue flow of uvc buffers will not + * happen. + */ + queue_work(video->async_wq, &video->pump); + } + /* + * Queue to the endpoint. The actual queueing to ep will + * only happen on one thread - the async_wq for bulk endpoints + * and this thread for isoc endpoints. + */ + ret = uvcg_video_usb_req_queue(video, to_queue, !is_bulk); + if (ret < 0) + uvcg_queue_cancel(queue, 0); } else { uvc_video_free_request(ureq, ep); } @@ -348,6 +482,7 @@ uvc_video_free_requests(struct uvc_video *video) INIT_LIST_HEAD(&video->ureqs); INIT_LIST_HEAD(&video->req_free); + INIT_LIST_HEAD(&video->req_ready); video->req_size = 0; return 0; } @@ -425,8 +560,7 @@ static void uvcg_video_pump(struct work_struct *work) struct usb_request *req = NULL; struct uvc_buffer *buf; unsigned long flags; - bool buf_done; - int ret; + int ret = 0; while (true) { if (!video->ep->enabled) @@ -455,15 +589,6 @@ static void uvcg_video_pump(struct work_struct *work) if (buf != NULL) { video->encode(req, video, buf); - buf_done = buf->state == UVC_BUF_STATE_DONE; - } else if (!(queue->flags & UVC_QUEUE_DISCONNECTED) && !is_bulk) { - /* - * No video buffer available; the queue is still connected and - * we're transferring over ISOC. Queue a 0 length request to - * prevent missed ISOC transfers. - */ - req->length = 0; - buf_done = false; } else { /* * Either the queue has been disconnected or no video buffer @@ -474,45 +599,25 @@ static void uvcg_video_pump(struct work_struct *work) break; } - /* - * With USB3 handling more requests at a higher speed, we can't - * afford to generate an interrupt for every request. Decide to - * 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_done || - !(video->req_int_count % - DIV_ROUND_UP(video->uvc_num_requests, 4))) { - video->req_int_count = 0; - req->no_interrupt = 0; - } else { - req->no_interrupt = 1; - } - - /* Queue the USB request */ - ret = uvcg_video_ep_queue(video, req); spin_unlock_irqrestore(&queue->irqlock, flags); + spin_lock_irqsave(&video->req_lock, flags); + /* For bulk end points we queue from the worker thread + * since we would preferably not want to wait on requests + * to be ready, in the uvcg_video_complete() handler. + * For isoc endpoints we add the request to the ready list + * and only queue it to the endpoint from the complete handler. + */ + ret = uvcg_video_usb_req_queue(video, req, is_bulk); + spin_unlock_irqrestore(&video->req_lock, flags); + if (ret < 0) { uvcg_queue_cancel(queue, 0); break; } - /* Endpoint now owns the request */ + /* The request is owned by the endpoint / ready list. */ req = NULL; - video->req_int_count++; } if (!req) @@ -581,8 +686,14 @@ uvcg_video_disable(struct uvc_video *video) uvc_video_free_request(req->context, video->ep); } + list_for_each_entry_safe(req, temp, &video->req_ready, list) { + list_del(&req->list); + uvc_video_free_request(req->context, video->ep); + } + INIT_LIST_HEAD(&video->ureqs); INIT_LIST_HEAD(&video->req_free); + INIT_LIST_HEAD(&video->req_ready); video->req_size = 0; spin_unlock_irqrestore(&video->req_lock, flags); @@ -636,7 +747,7 @@ int uvcg_video_enable(struct uvc_video *video) video->req_int_count = 0; - queue_work(video->async_wq, &video->pump); + uvc_video_ep_queue_initial_requests(video); return ret; } @@ -649,6 +760,7 @@ int uvcg_video_init(struct uvc_video *video, struct uvc_device *uvc) video->is_enabled = false; INIT_LIST_HEAD(&video->ureqs); INIT_LIST_HEAD(&video->req_free); + INIT_LIST_HEAD(&video->req_ready); spin_lock_init(&video->req_lock); INIT_WORK(&video->pump, uvcg_video_pump);