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

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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>
This commit is contained in:
Russell King 2009-02-21 21:38:56 +00:00 committed by Russell King
parent 308d333ad6
commit fa4e998999
1 changed files with 9 additions and 5 deletions
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14
arch/arm/mach-rpc/dma.c
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@ -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;