From: Thomas Petazzoni Date: Sat, 7 Jan 2012 12:52:37 +0000 (-0300) Subject: [media] cx231xx: use URB_NO_TRANSFER_DMA_MAP on URBs allocated with usb_alloc_urb() X-Git-Tag: v3.3-rc1~48^2~31 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7a6f6c29d264cdd2fe0eb3d923217eed5f0ad134;p=pandora-kernel.git [media] cx231xx: use URB_NO_TRANSFER_DMA_MAP on URBs allocated with usb_alloc_urb() URBs allocated with usb_alloc_urb() are allocated from DMA-coherent areas, and therefore it is not necessary to call dma_map_single() on such buffers. Worst, on ARM, calling dma_map_single() on a DMA-coherent buffer will trigger a BUG_ON() in arch/arm/mm/dma-mapping.c. Therefore, we mark all URBs allocated with usb_alloc_urb() with the URB_NO_TRANSFER_DMA_MAP transfer_flags, so that the USB core does not do dma_map_single()/dma_unmap_single() on those buffers. This is similar to 882787ff8fdeb0be790547ee9b22b281095e95da for the gspca driver, and has already been discussed on the linux-media list in the past: http://www.mail-archive.com/linux-media@vger.kernel.org/msg37086.html. Signed-off-by: Thomas Petazzoni Signed-off-by: Mauro Carvalho Chehab --- Reading git-diff-tree failed