On Thu, Mar 31, 2016 at 02:29:42PM +0200, Boris Brezillon wrote: > sg_alloc_table_from_buf() provides an easy solution to create an sg_table > from a virtual address pointer. This function takes care of dealing with > vmallocated buffers, buffer alignment, or DMA engine limitations (maximum > DMA transfer size). Please note that the DMA API does not take account of coherency of memory regions other than non-high/lowmem - there are specific extensions to deal with this. What this means is that having an API that takes any virtual address pointer, converts it to a scatterlist which is then DMA mapped, is unsafe. It'll be okay for PIPT and non-aliasing VIPT cache architectures, but for other cache architectures this will hide this problem and make review harder. -- RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net. -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
