media: uvcvideo: Move decode processing to process context
Newer high definition cameras, and cameras with multiple lenses such as the range of stereo-vision cameras now available have ever increasing data rates. The inclusion of a variable length packet header in URB packets mean that we must memcpy the frame data out to our destination 'manually'. This can result in data rates of up to 2 gigabits per second being processed. To improve efficiency, and maximise throughput, handle the URB decode processing through a work queue to move it from interrupt context, and allow multiple processors to work on URBs in parallel. Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
This commit is contained in:
Kieran Bingham
Mauro Carvalho Chehab
parent
ece41454c6
commit
b012186ace
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@ -401,6 +401,9 @@ static struct uvc_streaming *uvc_stream_by_id(struct uvc_device *dev, int id)
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static void uvc_stream_delete(struct uvc_streaming *stream)
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{
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if (stream->async_wq)
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destroy_workqueue(stream->async_wq);
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mutex_destroy(&stream->mutex);
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usb_put_intf(stream->intf);
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@ -425,6 +428,14 @@ static struct uvc_streaming *uvc_stream_new(struct uvc_device *dev,
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stream->intf = usb_get_intf(intf);
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stream->intfnum = intf->cur_altsetting->desc.bInterfaceNumber;
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/* Allocate a stream specific work queue for asynchronous tasks. */
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stream->async_wq = alloc_workqueue("uvcvideo", WQ_UNBOUND | WQ_HIGHPRI,
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0);
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if (!stream->async_wq) {
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uvc_stream_delete(stream);
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return NULL;
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}
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return stream;
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}
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@ -1094,21 +1094,54 @@ static int uvc_video_decode_start(struct uvc_streaming *stream,
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return data[0];
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}
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static void uvc_video_decode_data(struct uvc_streaming *stream,
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/*
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* uvc_video_decode_data_work: Asynchronous memcpy processing
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*
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* Copy URB data to video buffers in process context, releasing buffer
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* references and requeuing the URB when done.
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*/
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static void uvc_video_copy_data_work(struct work_struct *work)
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{
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struct uvc_urb *uvc_urb = container_of(work, struct uvc_urb, work);
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unsigned int i;
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int ret;
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for (i = 0; i < uvc_urb->async_operations; i++) {
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struct uvc_copy_op *op = &uvc_urb->copy_operations[i];
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memcpy(op->dst, op->src, op->len);
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/* Release reference taken on this buffer. */
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uvc_queue_buffer_release(op->buf);
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}
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ret = usb_submit_urb(uvc_urb->urb, GFP_KERNEL);
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if (ret < 0)
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uvc_printk(KERN_ERR, "Failed to resubmit video URB (%d).\n",
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ret);
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}
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static void uvc_video_decode_data(struct uvc_urb *uvc_urb,
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struct uvc_buffer *buf, const u8 *data, int len)
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{
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unsigned int maxlen, nbytes;
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void *mem;
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unsigned int active_op = uvc_urb->async_operations;
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struct uvc_copy_op *op = &uvc_urb->copy_operations[active_op];
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unsigned int maxlen;
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if (len <= 0)
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return;
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/* Copy the video data to the buffer. */
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maxlen = buf->length - buf->bytesused;
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mem = buf->mem + buf->bytesused;
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nbytes = min((unsigned int)len, maxlen);
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memcpy(mem, data, nbytes);
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buf->bytesused += nbytes;
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/* Take a buffer reference for async work. */
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kref_get(&buf->ref);
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op->buf = buf;
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op->src = data;
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op->dst = buf->mem + buf->bytesused;
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op->len = min_t(unsigned int, len, maxlen);
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buf->bytesused += op->len;
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/* Complete the current frame if the buffer size was exceeded. */
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if (len > maxlen) {
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@ -1116,6 +1149,8 @@ static void uvc_video_decode_data(struct uvc_streaming *stream,
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buf->error = 1;
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buf->state = UVC_BUF_STATE_READY;
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}
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uvc_urb->async_operations++;
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}
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static void uvc_video_decode_end(struct uvc_streaming *stream,
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@ -1324,7 +1359,7 @@ static void uvc_video_decode_isoc(struct uvc_urb *uvc_urb,
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uvc_video_decode_meta(stream, meta_buf, mem, ret);
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/* Decode the payload data. */
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uvc_video_decode_data(stream, buf, mem + ret,
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uvc_video_decode_data(uvc_urb, buf, mem + ret,
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urb->iso_frame_desc[i].actual_length - ret);
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/* Process the header again. */
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@ -1384,9 +1419,9 @@ static void uvc_video_decode_bulk(struct uvc_urb *uvc_urb,
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* sure buf is never dereferenced if NULL.
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*/
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/* Process video data. */
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/* Prepare video data for processing. */
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if (!stream->bulk.skip_payload && buf != NULL)
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uvc_video_decode_data(stream, buf, mem, len);
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uvc_video_decode_data(uvc_urb, buf, mem, len);
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/* Detect the payload end by a URB smaller than the maximum size (or
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* a payload size equal to the maximum) and process the header again.
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@ -1472,7 +1507,7 @@ static void uvc_video_complete(struct urb *urb)
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uvc_printk(KERN_WARNING, "Non-zero status (%d) in video "
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"completion handler.\n", urb->status);
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/* fall through */
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case -ENOENT: /* usb_kill_urb() called. */
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case -ENOENT: /* usb_poison_urb() called. */
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if (stream->frozen)
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return;
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/* fall through */
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@ -1494,12 +1529,26 @@ static void uvc_video_complete(struct urb *urb)
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spin_unlock_irqrestore(&qmeta->irqlock, flags);
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}
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/* Re-initialise the URB async work. */
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uvc_urb->async_operations = 0;
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/*
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* Process the URB headers, and optionally queue expensive memcpy tasks
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* to be deferred to a work queue.
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*/
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stream->decode(uvc_urb, buf, buf_meta);
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if ((ret = usb_submit_urb(urb, GFP_ATOMIC)) < 0) {
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uvc_printk(KERN_ERR, "Failed to resubmit video URB (%d).\n",
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ret);
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/* If no async work is needed, resubmit the URB immediately. */
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if (!uvc_urb->async_operations) {
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ret = usb_submit_urb(uvc_urb->urb, GFP_ATOMIC);
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if (ret < 0)
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uvc_printk(KERN_ERR,
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"Failed to resubmit video URB (%d).\n",
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ret);
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return;
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}
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queue_work(stream->async_wq, &uvc_urb->work);
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}
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/*
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@ -1594,20 +1643,22 @@ static int uvc_alloc_urb_buffers(struct uvc_streaming *stream,
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*/
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static void uvc_uninit_video(struct uvc_streaming *stream, int free_buffers)
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{
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struct urb *urb;
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unsigned int i;
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struct uvc_urb *uvc_urb;
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uvc_video_stats_stop(stream);
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for (i = 0; i < UVC_URBS; ++i) {
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struct uvc_urb *uvc_urb = &stream->uvc_urb[i];
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/*
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* We must poison the URBs rather than kill them to ensure that even
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* after the completion handler returns, any asynchronous workqueues
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* will be prevented from resubmitting the URBs.
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*/
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for_each_uvc_urb(uvc_urb, stream)
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usb_poison_urb(uvc_urb->urb);
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urb = uvc_urb->urb;
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if (urb == NULL)
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continue;
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flush_workqueue(stream->async_wq);
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usb_kill_urb(urb);
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usb_free_urb(urb);
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for_each_uvc_urb(uvc_urb, stream) {
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usb_free_urb(uvc_urb->urb);
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uvc_urb->urb = NULL;
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}
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@ -1932,6 +1983,7 @@ int uvc_video_init(struct uvc_streaming *stream)
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struct uvc_streaming_control *probe = &stream->ctrl;
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struct uvc_format *format = NULL;
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struct uvc_frame *frame = NULL;
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struct uvc_urb *uvc_urb;
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unsigned int i;
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int ret;
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@ -2017,6 +2069,10 @@ int uvc_video_init(struct uvc_streaming *stream)
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}
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}
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/* Prepare asynchronous work items. */
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for_each_uvc_urb(uvc_urb, stream)
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INIT_WORK(&uvc_urb->work, uvc_video_copy_data_work);
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return 0;
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}
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@ -493,6 +493,21 @@ struct uvc_stats_stream {
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#define UVC_METATADA_BUF_SIZE 1024
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/**
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* struct uvc_copy_op: Context structure to schedule asynchronous memcpy
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*
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* @buf: active buf object for this operation
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* @dst: copy destination address
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* @src: copy source address
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* @len: copy length
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*/
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struct uvc_copy_op {
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struct uvc_buffer *buf;
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void *dst;
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const __u8 *src;
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size_t len;
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};
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/**
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* struct uvc_urb - URB context management structure
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*
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@ -500,6 +515,9 @@ struct uvc_stats_stream {
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* @stream: UVC streaming context
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* @buffer: memory storage for the URB
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* @dma: DMA coherent addressing for the urb_buffer
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* @async_operations: counter to indicate the number of copy operations
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* @copy_operations: work descriptors for asynchronous copy operations
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* @work: work queue entry for asynchronous decode
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*/
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struct uvc_urb {
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struct urb *urb;
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@ -507,6 +525,10 @@ struct uvc_urb {
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char *buffer;
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dma_addr_t dma;
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unsigned int async_operations;
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struct uvc_copy_op copy_operations[UVC_MAX_PACKETS];
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struct work_struct work;
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};
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struct uvc_streaming {
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@ -539,6 +561,7 @@ struct uvc_streaming {
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/* Buffers queue. */
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unsigned int frozen : 1;
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struct uvc_video_queue queue;
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struct workqueue_struct *async_wq;
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void (*decode)(struct uvc_urb *uvc_urb, struct uvc_buffer *buf,
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struct uvc_buffer *meta_buf);
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@ -592,6 +615,11 @@ struct uvc_streaming {
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} clock;
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};
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#define for_each_uvc_urb(uvc_urb, uvc_streaming) \
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for ((uvc_urb) = &(uvc_streaming)->uvc_urb[0]; \
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(uvc_urb) < &(uvc_streaming)->uvc_urb[UVC_URBS]; \
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++(uvc_urb))
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struct uvc_device_info {
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u32 quirks;
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u32 meta_format;
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