[ARM] dma: RiscPC: don't modify DMA SG entries

We should not be modifying the scatterlist passed to us from the
driver code; doing so breaks assumptions made by the DMA API code,
and could cause problems if the driver retries a transfer using an
old scatterlist.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/mach-rpc/dma.c b/arch/arm/mach-rpc/dma.c
index 1f77cdca26e98483153020717d49ad0653634975..c47d974d52bdacbe5fddcc40b9a630c2f5a914f0 100644 (file)
--- a/arch/arm/mach-rpc/dma.c
+++ b/arch/arm/mach-rpc/dma.c
@@ -32,6 +32,8 @@ struct iomd_dma {
        unsigned long           base;           /* Controller base address */
        int                     irq;            /* Controller IRQ */
        struct scatterlist      cur_sg;         /* Current controller buffer */
+       dma_addr_t              dma_addr;
+       unsigned int            dma_len;
 };
 
 #if 0
@@ -57,10 +59,10 @@ static void iomd_get_next_sg(struct scatterlist *sg, struct iomd_dma *idma)
        unsigned long end, offset, flags = 0;
 
        if (idma->dma.sg) {
-               sg->dma_address = idma->dma.sg->dma_address;
+               sg->dma_address = idma->dma_addr;
                offset = sg->dma_address & ~PAGE_MASK;
 
-               end = offset + idma->dma.sg->length;
+               end = offset + idma->dma_len;
 
                if (end > PAGE_SIZE)
                        end = PAGE_SIZE;
@@ -70,12 +72,14 @@ static void iomd_get_next_sg(struct scatterlist *sg, struct iomd_dma *idma)
 
                sg->length = end - TRANSFER_SIZE;
 
-               idma->dma.sg->length -= end - offset;
-               idma->dma.sg->dma_address += end - offset;
+               idma->dma_len -= end - offset;
+               idma->dma_addr += end - offset;
 
-               if (idma->dma.sg->length == 0) {
+               if (idma->dma_len == 0) {
                        if (idma->dma.sgcount > 1) {
                                idma->dma.sg = sg_next(idma->dma.sg);
+                               idma->dma_addr = idma->dma.sg->dma_address;
+                               idma->dma_len = idma->dma.sg->length;
                                idma->dma.sgcount--;
                        } else {
                                idma->dma.sg = NULL;