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Commit 3b45d638 authored by Andrea Paterniani's avatar Andrea Paterniani Committed by Linus Torvalds
Browse files

spi_imx: full duplex dma corruption bugfix 



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.

Signed-off-by: default avatarAndrea Paterniani <a.paterniani@swapp-eng.it>
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 b3b4dc88

drivers/spi/spi_imx.c

+22 −23
Original line number Diff line number Diff line
@@ -506,20 +506,6 @@ static int map_dma_buffers(struct driver_data *drv_data) 
	if (!IS_DMA_ALIGNED(drv_data->rx) || !IS_DMA_ALIGNED(drv_data->tx))

		return -1;



	/* NULL rx means write-only transfer and no map needed

	   since rx DMA will not be used */

	if (drv_data->rx) {

		buf = drv_data->rx;

		drv_data->rx_dma = dma_map_single(

					dev,

					buf,

					drv_data->len,

					DMA_FROM_DEVICE);

		if (dma_mapping_error(dev, drv_data->rx_dma))

			return -1;

		drv_data->rx_dma_needs_unmap = 1;

	}



	if (drv_data->tx == NULL) {

		/* Read only message --> use drv_data->dummy_dma_buf for dummy

		   writes to achive reads */
@@ -533,17 +519,30 @@ static int map_dma_buffers(struct driver_data *drv_data) 
					buf,

					drv_data->tx_map_len,

					DMA_TO_DEVICE);

	if (dma_mapping_error(dev, drv_data->tx_dma)) {

		if (drv_data->rx_dma) {

			dma_unmap_single(dev,

					drv_data->rx_dma,

	if (dma_mapping_error(dev, drv_data->tx_dma))

		return -1;

	drv_data->tx_dma_needs_unmap = 1;



	/* NULL rx means write-only transfer and no map needed

	 * since rx DMA will not be used */

	if (drv_data->rx) {

		buf = drv_data->rx;

		drv_data->rx_dma = dma_map_single(dev,

						buf,

						drv_data->len,

						DMA_FROM_DEVICE);

			drv_data->rx_dma_needs_unmap = 0;

		if (dma_mapping_error(dev, drv_data->rx_dma)) {

			if (drv_data->tx_dma) {

				dma_unmap_single(dev,

						drv_data->tx_dma,

						drv_data->tx_map_len,

						DMA_TO_DEVICE);

				drv_data->tx_dma_needs_unmap = 0;

			}

			return -1;

		}

	drv_data->tx_dma_needs_unmap = 1;

		drv_data->rx_dma_needs_unmap = 1;

	}



	return 0;

}