dmaengine: add DMA_COMPL_SKIP_{SRC,DEST}_UNMAP flags to control dma unmap

In some cases client code may need the dma-driver to skip the unmap of source
and/or destination buffers.  Setting these flags indicates to the driver to
skip the unmap step.  In this regard async_xor is currently broken in that it
allows the destination buffer to be unmapped while an operation is still in
progress, i.e. when the number of sources exceeds the hardware channel's
maximum (fixed in a subsequent patch).

Acked-by: Saeed Bishara <saeed@marvell.com>
Acked-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Acked-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 16 insertions, 6 deletions

diff --git a/drivers/dma/mv_xor.c b/drivers/dma/mv_xor.c
index 8239cfdbc2e6..a4e4494663bf 100644
--- a/drivers/dma/mv_xor.c
+++ b/drivers/dma/mv_xor.c
@@ -308,13 +308,23 @@ mv_xor_run_tx_complete_actions(struct mv_xor_desc_slot *desc,
                         struct device *dev =
                                 &mv_chan->device->pdev->dev;
                         u32 len = unmap->unmap_len;
-                        u32 src_cnt = unmap->unmap_src_cnt;
-                        dma_addr_t addr = mv_desc_get_dest_addr(unmap);
+                        enum dma_ctrl_flags flags = desc->async_tx.flags;
+                        u32 src_cnt;
+                        dma_addr_t addr;
 
-                        dma_unmap_page(dev, addr, len, DMA_FROM_DEVICE);
-                        while (src_cnt--) {
-                                addr = mv_desc_get_src_addr(unmap, src_cnt);
-                                dma_unmap_page(dev, addr, len, DMA_TO_DEVICE);
+                        if (!(flags & DMA_COMPL_SKIP_DEST_UNMAP)) {
+                                addr = mv_desc_get_dest_addr(unmap);
+                                dma_unmap_page(dev, addr, len, DMA_FROM_DEVICE);
+                        }
+
+                        if (!(flags & DMA_COMPL_SKIP_SRC_UNMAP)) {
+                                src_cnt = unmap->unmap_src_cnt;
+                                while (src_cnt--) {
+                                        addr = mv_desc_get_src_addr(unmap,
+                                                                    src_cnt);
+                                        dma_unmap_page(dev, addr, len,
+                                                       DMA_TO_DEVICE);
+                                }
                         }
                         desc->group_head = NULL;
                 }