Hello, This series has been extracted from another series [1] adding support for DMA operations in a NAND driver. The reason I decided to post those patches separately is because they are touching core stuff, and I'd like to have feedback on these specific aspects. The idea is to provide a generic function creating an sg_table from a virtual pointer and a length. This operation is complicated by the different memory regions exposed in kernel space. For example, you have the lowmem region, which guarantees that buffers are physically contiguous, while the vmalloc region does not. sg_alloc_table_from_buf() detects in which memory region your buffer reside, and takes the appropriate precautions when creating the sg_table. This function also takes an extract parameter, allowing one to specify extra constraints, like the maximum DMA segment size, the required and the preferred alignment. Patch 1 and 2 are implementing sg_alloc_table_from_buf() (patch 1 is needed to properly detect buffers residing in the highmem/kmap area). Patch 3 is making use of sg_alloc_table_from_buf() in the spi_map_buf() function (hopefully, other subsystems/drivers will be able to easily switch to this function too). Patch 4 is implementing what I really need: generic functions to map/unmap a virtual buffer passed through mtd->_read/_write(). I'm not exactly a DMA or MM experts, so that would be great to have feedbacks on this approach. That's why I added so many people in Cc even if they're not directly impacted by those patches. Let me know if you want me to drop/add people from/to the recipient list. Thanks. Best Regards, Boris [1]http://www.spinics.net/lists/arm-kernel/msg493552.html Boris Brezillon (4): mm: add is_highmem_addr() helper scatterlist: add sg_alloc_table_from_buf() helper spi: use sg_alloc_table_from_buf() mtd: provide helper to prepare buffers for DMA operations drivers/mtd/mtdcore.c | 66 ++++++++++++++++ drivers/spi/spi.c | 45 ++--------- include/linux/highmem.h | 13 ++++ include/linux/mtd/mtd.h | 25 ++++++ include/linux/scatterlist.h | 24 ++++++ lib/scatterlist.c | 183 ++++++++++++++++++++++++++++++++++++++++++++ 6 files changed, 316 insertions(+), 40 deletions(-) -- 2.5.0 -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
