Hello,
On an x86 platform, we have managed to use a Hauppauge USB Live 2
capture device with the cx231xx on a 3.0 kernel with the patch at [1].
Things work nicely.
However, using a similar 3.0 kernel with the exact same device on an
ARM platform (BeagleBoard-XM), starting a V4L application to capture
the video immediately triggers the following BUG_ON in
arch/arm/mm/dma-mapping.c:
429 void ___dma_single_cpu_to_dev(const void *kaddr, size_t size,
430 enum dma_data_direction dir)
431 {
432 unsigned long paddr;
433
434 BUG_ON(!virt_addr_valid(kaddr) || !virt_addr_valid(kaddr + size -
1));
This problem looks similar to the problem fixed on the gspca driver by:
commit 882787ff8fdeb0be790547ee9b22b281095e95da
Author: Jason Wang <[email protected]>
Date: Fri Sep 3 06:57:19 2010 -0300
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 <[email protected]>
Signed-off-by: Jean-François Moine <[email protected]>
Cc: [email protected]
Signed-off-by: Mauro Carvalho Chehab <[email protected]>
I guess the cx231xx driver is trying to DMA-map buffers whose location
is not appropriate for DMA-mapping, because they are already in an DMA
coherent region. Is the fix just to add the same
URB_NO_TRANSFER_DMA_MAP to the urb->transfer_flags ? Or is it something
completely different ?
Thanks!
Thomas
[1]
https://github.com/torvalds/linux/commit/992299e84a4891275ea5924e30b66ce39a701e5e#drivers/media/video/cx231xx
--
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
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