From: Kieran Bingham Date: Wed, 22 Mar 2017 09:42:52 +0000 (-0400) Subject: media: uvcvideo: Move decode processing to process context X-Git-Tag: for-linus-20190104~135^2~94 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=b012186acef57b683e3c22ba758d60c3780db16a;p=linux-2.6-block.git 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 Signed-off-by: Laurent Pinchart Signed-off-by: Mauro Carvalho Chehab --- diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c index afb44d1c9d04..b62cbd800111 100644 --- a/drivers/media/usb/uvc/uvc_driver.c +++ b/drivers/media/usb/uvc/uvc_driver.c @@ -401,6 +401,9 @@ static struct uvc_streaming *uvc_stream_by_id(struct uvc_device *dev, int id) static void uvc_stream_delete(struct uvc_streaming *stream) { + if (stream->async_wq) + destroy_workqueue(stream->async_wq); + mutex_destroy(&stream->mutex); usb_put_intf(stream->intf); @@ -425,6 +428,14 @@ static struct uvc_streaming *uvc_stream_new(struct uvc_device *dev, stream->intf = usb_get_intf(intf); stream->intfnum = intf->cur_altsetting->desc.bInterfaceNumber; + /* Allocate a stream specific work queue for asynchronous tasks. */ + stream->async_wq = alloc_workqueue("uvcvideo", WQ_UNBOUND | WQ_HIGHPRI, + 0); + if (!stream->async_wq) { + uvc_stream_delete(stream); + return NULL; + } + return stream; } diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c index 7a7779e1b466..e19bdf089cc4 100644 --- a/drivers/media/usb/uvc/uvc_video.c +++ b/drivers/media/usb/uvc/uvc_video.c @@ -1094,21 +1094,54 @@ static int uvc_video_decode_start(struct uvc_streaming *stream, return data[0]; } -static void uvc_video_decode_data(struct uvc_streaming *stream, +/* + * uvc_video_decode_data_work: Asynchronous memcpy processing + * + * Copy URB data to video buffers in process context, releasing buffer + * references and requeuing the URB when done. + */ +static void uvc_video_copy_data_work(struct work_struct *work) +{ + struct uvc_urb *uvc_urb = container_of(work, struct uvc_urb, work); + unsigned int i; + int ret; + + for (i = 0; i < uvc_urb->async_operations; i++) { + struct uvc_copy_op *op = &uvc_urb->copy_operations[i]; + + memcpy(op->dst, op->src, op->len); + + /* Release reference taken on this buffer. */ + uvc_queue_buffer_release(op->buf); + } + + ret = usb_submit_urb(uvc_urb->urb, GFP_KERNEL); + if (ret < 0) + uvc_printk(KERN_ERR, "Failed to resubmit video URB (%d).\n", + ret); +} + +static void uvc_video_decode_data(struct uvc_urb *uvc_urb, struct uvc_buffer *buf, const u8 *data, int len) { - unsigned int maxlen, nbytes; - void *mem; + unsigned int active_op = uvc_urb->async_operations; + struct uvc_copy_op *op = &uvc_urb->copy_operations[active_op]; + unsigned int maxlen; if (len <= 0) return; - /* Copy the video data to the buffer. */ maxlen = buf->length - buf->bytesused; - mem = buf->mem + buf->bytesused; - nbytes = min((unsigned int)len, maxlen); - memcpy(mem, data, nbytes); - buf->bytesused += nbytes; + + /* Take a buffer reference for async work. */ + kref_get(&buf->ref); + + op->buf = buf; + op->src = data; + op->dst = buf->mem + buf->bytesused; + op->len = min_t(unsigned int, len, maxlen); + + buf->bytesused += op->len; /* Complete the current frame if the buffer size was exceeded. */ if (len > maxlen) { @@ -1116,6 +1149,8 @@ static void uvc_video_decode_data(struct uvc_streaming *stream, buf->error = 1; buf->state = UVC_BUF_STATE_READY; } + + uvc_urb->async_operations++; } static void uvc_video_decode_end(struct uvc_streaming *stream, @@ -1324,7 +1359,7 @@ static void uvc_video_decode_isoc(struct uvc_urb *uvc_urb, uvc_video_decode_meta(stream, meta_buf, mem, ret); /* Decode the payload data. */ - uvc_video_decode_data(stream, buf, mem + ret, + uvc_video_decode_data(uvc_urb, buf, mem + ret, urb->iso_frame_desc[i].actual_length - ret); /* Process the header again. */ @@ -1384,9 +1419,9 @@ static void uvc_video_decode_bulk(struct uvc_urb *uvc_urb, * sure buf is never dereferenced if NULL. */ - /* Process video data. */ + /* Prepare video data for processing. */ if (!stream->bulk.skip_payload && buf != NULL) - uvc_video_decode_data(stream, buf, mem, len); + uvc_video_decode_data(uvc_urb, buf, mem, len); /* Detect the payload end by a URB smaller than the maximum size (or * a payload size equal to the maximum) and process the header again. @@ -1472,7 +1507,7 @@ static void uvc_video_complete(struct urb *urb) uvc_printk(KERN_WARNING, "Non-zero status (%d) in video " "completion handler.\n", urb->status); /* fall through */ - case -ENOENT: /* usb_kill_urb() called. */ + case -ENOENT: /* usb_poison_urb() called. */ if (stream->frozen) return; /* fall through */ @@ -1494,12 +1529,26 @@ static void uvc_video_complete(struct urb *urb) spin_unlock_irqrestore(&qmeta->irqlock, flags); } + /* Re-initialise the URB async work. */ + uvc_urb->async_operations = 0; + + /* + * Process the URB headers, and optionally queue expensive memcpy tasks + * to be deferred to a work queue. + */ stream->decode(uvc_urb, buf, buf_meta); - if ((ret = usb_submit_urb(urb, GFP_ATOMIC)) < 0) { - uvc_printk(KERN_ERR, "Failed to resubmit video URB (%d).\n", - ret); + /* If no async work is needed, resubmit the URB immediately. */ + if (!uvc_urb->async_operations) { + ret = usb_submit_urb(uvc_urb->urb, GFP_ATOMIC); + if (ret < 0) + uvc_printk(KERN_ERR, + "Failed to resubmit video URB (%d).\n", + ret); + return; } + + queue_work(stream->async_wq, &uvc_urb->work); } /* @@ -1594,20 +1643,22 @@ static int uvc_alloc_urb_buffers(struct uvc_streaming *stream, */ static void uvc_uninit_video(struct uvc_streaming *stream, int free_buffers) { - struct urb *urb; - unsigned int i; + struct uvc_urb *uvc_urb; uvc_video_stats_stop(stream); - for (i = 0; i < UVC_URBS; ++i) { - struct uvc_urb *uvc_urb = &stream->uvc_urb[i]; + /* + * We must poison the URBs rather than kill them to ensure that even + * after the completion handler returns, any asynchronous workqueues + * will be prevented from resubmitting the URBs. + */ + for_each_uvc_urb(uvc_urb, stream) + usb_poison_urb(uvc_urb->urb); - urb = uvc_urb->urb; - if (urb == NULL) - continue; + flush_workqueue(stream->async_wq); - usb_kill_urb(urb); - usb_free_urb(urb); + for_each_uvc_urb(uvc_urb, stream) { + usb_free_urb(uvc_urb->urb); uvc_urb->urb = NULL; } @@ -1932,6 +1983,7 @@ int uvc_video_init(struct uvc_streaming *stream) struct uvc_streaming_control *probe = &stream->ctrl; struct uvc_format *format = NULL; struct uvc_frame *frame = NULL; + struct uvc_urb *uvc_urb; unsigned int i; int ret; @@ -2017,6 +2069,10 @@ int uvc_video_init(struct uvc_streaming *stream) } } + /* Prepare asynchronous work items. */ + for_each_uvc_urb(uvc_urb, stream) + INIT_WORK(&uvc_urb->work, uvc_video_copy_data_work); + return 0; } diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h index 92a17f011bf2..c7e96d52decc 100644 --- a/drivers/media/usb/uvc/uvcvideo.h +++ b/drivers/media/usb/uvc/uvcvideo.h @@ -493,6 +493,21 @@ struct uvc_stats_stream { #define UVC_METATADA_BUF_SIZE 1024 +/** + * struct uvc_copy_op: Context structure to schedule asynchronous memcpy + * + * @buf: active buf object for this operation + * @dst: copy destination address + * @src: copy source address + * @len: copy length + */ +struct uvc_copy_op { + struct uvc_buffer *buf; + void *dst; + const __u8 *src; + size_t len; +}; + /** * struct uvc_urb - URB context management structure * @@ -500,6 +515,9 @@ struct uvc_stats_stream { * @stream: UVC streaming context * @buffer: memory storage for the URB * @dma: DMA coherent addressing for the urb_buffer + * @async_operations: counter to indicate the number of copy operations + * @copy_operations: work descriptors for asynchronous copy operations + * @work: work queue entry for asynchronous decode */ struct uvc_urb { struct urb *urb; @@ -507,6 +525,10 @@ struct uvc_urb { char *buffer; dma_addr_t dma; + + unsigned int async_operations; + struct uvc_copy_op copy_operations[UVC_MAX_PACKETS]; + struct work_struct work; }; struct uvc_streaming { @@ -539,6 +561,7 @@ struct uvc_streaming { /* Buffers queue. */ unsigned int frozen : 1; struct uvc_video_queue queue; + struct workqueue_struct *async_wq; void (*decode)(struct uvc_urb *uvc_urb, struct uvc_buffer *buf, struct uvc_buffer *meta_buf); @@ -592,6 +615,11 @@ struct uvc_streaming { } clock; }; +#define for_each_uvc_urb(uvc_urb, uvc_streaming) \ + for ((uvc_urb) = &(uvc_streaming)->uvc_urb[0]; \ + (uvc_urb) < &(uvc_streaming)->uvc_urb[UVC_URBS]; \ + ++(uvc_urb)) + struct uvc_device_info { u32 quirks; u32 meta_format;