Re: [PATCH] drm/cma: Use dma_mmap_writecombine() to mmap buffer

On Sun, Mar 2, 2014 at 8:09 PM, Laurent Pinchart laurent.pinchart+renesas@ideasonboard.com wrote:

The GEM CMA helpers uses a custom mmap implementation based on remap_pfn_range(). While this works when the buffer DMA and physical addresses are identical, it fails to take IOMMU into account and tries to mmap the buffer to userspace using the DMA virtual address instead of the physical address. This results in mapping random physical pages when the device is behind an IOMMU.

Use the DMA mapping dma_mmap_writecombine() function instead.

Signed-off-by: Laurent Pinchart laurent.pinchart+renesas@ideasonboard.com

Tested-by: Philipp Zabel philipp.zabel@gmail.com

regards Philipp