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V4L/DVB: gspca - main: Fix a crash of some webcams on ARM arch

When plugging some webcams on ARM, the system crashes.
This is because we alloc buffer for an urb through usb_buffer_alloc,
the alloced buffer is already in DMA coherent region, so we should
set the flag of this urb to URB_NO_TRANSFER_DMA_MAP, otherwise when
we submit this urb, the hcd core will handle this address as an
non-DMA address and call dma_map_single/sg to map it. On arm
architecture, dma_map_single a DMA coherent address will be catched
by a BUG_ON().

Signed-off-by: Jason Wang <>
Signed-off-by: Jean-François Moine <>
Signed-off-by: Mauro Carvalho Chehab <>
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1 parent 67b459d commit 7f406f6dba6c65174f96ef13be3f0a594f5b4c39 Jason Wang committed with Sean Cross Sep 3, 2010
Showing with 1 addition and 0 deletions.
  1. +1 −0 drivers/media/video/gspca/gspca.c
@@ -223,6 +223,7 @@ static int alloc_and_submit_int_urb(struct gspca_dev *gspca_dev,
usb_rcvintpipe(dev, ep->bEndpointAddress),
buffer, buffer_len,
int_irq, (void *)gspca_dev, interval);
+ urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
gspca_dev->int_urb = urb;
ret = usb_submit_urb(urb, GFP_KERNEL);
if (ret < 0) {

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