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spi: au1550_spi full duplex dma fix

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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>
This commit is contained in:
Jan Nikitenko 2008-12-01 13:13:56 -08:00 committed by Linus Torvalds
parent 6a010b56e9
commit 4e253d2300
1 changed files with 16 additions and 10 deletions
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26
drivers/spi/au1550_spi.c
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@ -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;