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V4L/DVB (7565): em28xx: fix buffer underrun handling
This patch fixes three related issues and a fourth trivial one: - Use buffers even if no-one's currently waiting for them (fixes underrun issues); - Don't return incomplete/mangled frames at the start of streaming and in the case of buffer underruns; - Fix an issue which could cause the driver to write to a buffer that's been freed after videobuf_queue_cancel is called (exposed by the previous two fixes - for some reason, ignoring buffers that weren't being waited on worked around the issue); - Fix a bug which could cause only one field to be filled in the first buffer (or first few buffers) after streaming is started. Signed-off-by: Aidan Thornton <makosoft@googlemail.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
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@ -266,7 +266,7 @@ static inline void print_err_status(struct em28xx *dev,
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/*
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* video-buf generic routine to get the next available buffer
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*/
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static inline int get_next_buf(struct em28xx_dmaqueue *dma_q,
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static inline void get_next_buf(struct em28xx_dmaqueue *dma_q,
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struct em28xx_buffer **buf)
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{
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struct em28xx *dev = container_of(dma_q, struct em28xx, vidq);
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@ -274,39 +274,21 @@ static inline int get_next_buf(struct em28xx_dmaqueue *dma_q,
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if (list_empty(&dma_q->active)) {
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em28xx_isocdbg("No active queue to serve\n");
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dev->isoc_ctl.buf = NULL;
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return 0;
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}
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/* Check if the last buffer were fully filled */
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*buf = dev->isoc_ctl.buf;
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/* Nobody is waiting on this buffer - discards */
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if (*buf && !waitqueue_active(&(*buf)->vb.done)) {
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dev->isoc_ctl.buf = NULL;
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*buf = NULL;
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return;
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}
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/* Returns the last buffer, to be filled with remaining data */
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if (*buf)
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return 1;
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/* Get the next buffer */
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*buf = list_entry(dma_q->active.next, struct em28xx_buffer, vb.queue);
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/* Nobody is waiting on the next buffer. returns */
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if (!*buf || !waitqueue_active(&(*buf)->vb.done)) {
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em28xx_isocdbg("No active queue to serve\n");
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return 0;
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}
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/* Cleans up buffer - Usefull for testing for frame/URB loss */
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outp = videobuf_to_vmalloc(&(*buf)->vb);
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memset(outp, 0, (*buf)->vb.size);
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dev->isoc_ctl.buf = *buf;
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return 1;
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return;
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}
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/*
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@ -317,7 +299,7 @@ static inline int em28xx_isoc_copy(struct urb *urb)
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struct em28xx_buffer *buf;
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struct em28xx_dmaqueue *dma_q = urb->context;
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struct em28xx *dev = container_of(dma_q, struct em28xx, vidq);
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unsigned char *outp;
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unsigned char *outp = NULL;
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int i, len = 0, rc = 1;
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unsigned char *p;
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@ -333,10 +315,8 @@ static inline int em28xx_isoc_copy(struct urb *urb)
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return 0;
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}
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rc = get_next_buf(dma_q, &buf);
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if (rc <= 0)
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return rc;
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buf = dev->isoc_ctl.buf;
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if (buf != NULL)
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outp = videobuf_to_vmalloc(&buf->vb);
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for (i = 0; i < urb->number_of_packets; i++) {
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@ -374,23 +354,26 @@ static inline int em28xx_isoc_copy(struct urb *urb)
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em28xx_isocdbg("Video frame %d, length=%i, %s\n", p[2],
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len, (p[2] & 1)? "odd" : "even");
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if (!(p[2] & 1)) {
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if (buf != NULL)
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buffer_filled(dev, dma_q, buf);
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get_next_buf(dma_q, &buf);
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if (buf == NULL)
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outp = NULL;
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else
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outp = videobuf_to_vmalloc(&buf->vb);
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}
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if (buf != NULL) {
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if (p[2] & 1)
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buf->top_field = 0;
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else
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buf->top_field = 1;
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// if (dev->isoc_ctl.last_field && !buf->top_field) {
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if (dev->isoc_ctl.last_field != buf->top_field) {
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buffer_filled(dev, dma_q, buf);
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rc = get_next_buf(dma_q, &buf);
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if (rc <= 0)
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return rc;
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outp = videobuf_to_vmalloc(&buf->vb);
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}
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dev->isoc_ctl.last_field = buf->top_field;
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dma_q->pos = 0;
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}
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if (buf != NULL)
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em28xx_copy_video(dev, dma_q, buf, p, outp, len);
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}
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return rc;
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@ -597,12 +580,29 @@ buffer_setup(struct videobuf_queue *vq, unsigned int *count, unsigned int *size)
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return 0;
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}
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/* This is called *without* dev->slock held; please keep it that way */
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static void free_buffer(struct videobuf_queue *vq, struct em28xx_buffer *buf)
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{
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struct em28xx_fh *fh = vq->priv_data;
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struct em28xx *dev = fh->dev;
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unsigned long flags = 0;
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if (in_interrupt())
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BUG();
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videobuf_waiton(&buf->vb, 0, 0);
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/* We used to wait for the buffer to finish here, but this didn't work
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because, as we were keeping the state as VIDEOBUF_QUEUED,
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videobuf_queue_cancel marked it as finished for us.
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(Also, it could wedge forever if the hardware was misconfigured.)
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This should be safe; by the time we get here, the buffer isn't
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queued anymore. If we ever start marking the buffers as
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VIDEOBUF_ACTIVE, it won't be, though.
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*/
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spin_lock_irqsave(&dev->slock, flags);
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if (dev->isoc_ctl.buf == buf)
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dev->isoc_ctl.buf = NULL;
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spin_unlock_irqrestore(&dev->slock, flags);
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videobuf_vmalloc_free(&buf->vb);
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buf->vb.state = VIDEOBUF_NEEDS_INIT;
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}
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@ -114,9 +114,6 @@ struct em28xx_usb_isoc_ctl {
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/* Stores already requested buffers */
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struct em28xx_buffer *buf;
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/* Store last filled frame */
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int last_field;
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/* Stores the number of received fields */
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int nfields;
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};
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