Commit 4e253d23 authored by Jan Nikitenko's avatar Jan Nikitenko Committed by Linus Torvalds
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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: default avatarJan Nikitenko <jan.nikitenko@gmail.com>
Signed-off-by: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 6a010b56

drivers/spi/au1550_spi.c

+16 −10
Original line number Diff line number Diff line
@@ -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;

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