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authorJan Nikitenko <jan.nikitenko@gmail.com>2008-12-01 13:13:56 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2008-12-01 19:55:24 -0800
commit4e253d23003b54c88d0919d6088be74f00eec3c7 (patch)
tree418741f7add461e32f4c2801e8a693f9dbd0455b
parent6a010b56e9bd2fdb32efd153e1a08305949b6b53 (diff)
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spi: au1550_spi full duplex dma fix
Fix unsafe order in dma mapping operation: always flush data from the cache *BEFORE* invalidating it, to allow full duplex transfers where the same buffer may be used for both writes and reads. Tested with mmc-spi. Signed-off-by: Jan Nikitenko <jan.nikitenko@gmail.com> Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--drivers/spi/au1550_spi.c26
1 files changed, 16 insertions, 10 deletions
diff --git a/drivers/spi/au1550_spi.c b/drivers/spi/au1550_spi.c
index 87b73e0169c5..b02f25c702fd 100644
--- a/drivers/spi/au1550_spi.c
+++ b/drivers/spi/au1550_spi.c
@@ -369,10 +369,23 @@ static int au1550_spi_dma_txrxb(struct spi_device *spi, struct spi_transfer *t)
dma_rx_addr = t->rx_dma;
/*
- * check if buffers are already dma mapped, map them otherwise
+ * check if buffers are already dma mapped, map them otherwise:
+ * - first map the TX buffer, so cache data gets written to memory
+ * - then map the RX buffer, so that cache entries (with
+ * soon-to-be-stale data) get removed
* use rx buffer in place of tx if tx buffer was not provided
* use temp rx buffer (preallocated or realloc to fit) for rx dma
*/
+ if (t->tx_buf) {
+ if (t->tx_dma == 0) { /* if DMA_ADDR_INVALID, map it */
+ dma_tx_addr = dma_map_single(hw->dev,
+ (void *)t->tx_buf,
+ t->len, DMA_TO_DEVICE);
+ if (dma_mapping_error(hw->dev, dma_tx_addr))
+ dev_err(hw->dev, "tx dma map error\n");
+ }
+ }
+
if (t->rx_buf) {
if (t->rx_dma == 0) { /* if DMA_ADDR_INVALID, map it */
dma_rx_addr = dma_map_single(hw->dev,
@@ -396,15 +409,8 @@ static int au1550_spi_dma_txrxb(struct spi_device *spi, struct spi_transfer *t)
dma_sync_single_for_device(hw->dev, dma_rx_addr,
t->len, DMA_FROM_DEVICE);
}
- if (t->tx_buf) {
- if (t->tx_dma == 0) { /* if DMA_ADDR_INVALID, map it */
- dma_tx_addr = dma_map_single(hw->dev,
- (void *)t->tx_buf,
- t->len, DMA_TO_DEVICE);
- if (dma_mapping_error(hw->dev, dma_tx_addr))
- dev_err(hw->dev, "tx dma map error\n");
- }
- } else {
+
+ if (!t->tx_buf) {
dma_sync_single_for_device(hw->dev, dma_rx_addr,
t->len, DMA_BIDIRECTIONAL);
hw->tx = hw->rx;