Hi Franklin, On Thu, 10 Mar 2016 17:56:42 -0600 Franklin S Cooper Jr <fcoo...@ti.com> wrote:
> Based on DMA documentation and testing using high memory buffer when > doing dma transfers can lead to various issues including kernel > panics. I guess it all comes from the vmalloced buffer case, which are not guaranteed to be physically contiguous (one of the DMA requirement, unless you have an iommu). > > To workaround this simply use cpu copy. The amount of high memory > buffers used are very uncommon so no noticeable performance hit should > be seen. Hm, that's not necessarily true. UBI and UBIFS allocate their buffers using vmalloc (vmalloced buffers fall in the high_memory region), and those are likely to be dis-contiguous if you have NANDs with pages > 4k. I recently posted patches to ease sg_table creation from any kind of virtual address [1][2]. Can you try them and let me know if it fixes your problem? Thanks, Boris [1]https://lkml.org/lkml/2016/3/8/276 [2]https://lkml.org/lkml/2016/3/8/277 -- Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com
