Commit 5a9a62bb authored Jun 01, 2007 by Haavard Skinnemoen Committed by Linus Torvalds Jun 01, 2007

atmel_spi dma address bugfix



When either rx_buf or tx_buf is not being used, i.e.  for plain read- or
write operations, the atmel_spi uses a fixed-size DMA buffer instead.  If
the transfer is longer than the size of this buffer, it is split into
multiple DMA transfers.

When the transfer is split like this, the atmel_spi driver ends up using
the same DMA address again and again even for the buffer that came from the
user, which is of course wrong.  Fix this by adding the number of bytes
already transferred to the DMA address so that the data ends up in the
right place.

Thanks to Wu Xuan for discovering this bug.

Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.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>

parent e88b34ba

drivers/spi/atmel_spi.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -113,16 +113,16 @@ static void atmel_spi_next_xfer(struct spi_master *master,

		len = as->remaining_bytes;

		tx_dma = xfer->tx_dma;
		rx_dma = xfer->rx_dma;
		tx_dma = xfer->tx_dma + xfer->len - len;
		rx_dma = xfer->rx_dma + xfer->len - len;

		/* use scratch buffer only when rx or tx data is unspecified */
		if (rx_dma == INVALID_DMA_ADDRESS) {
		if (!xfer->rx_buf) {
		rx_dma = as->buffer_dma;
		if (len > BUFFER_SIZE)
		len = BUFFER_SIZE;
		}
		if (tx_dma == INVALID_DMA_ADDRESS) {
		if (!xfer->tx_buf) {
		tx_dma = as->buffer_dma;
		if (len > BUFFER_SIZE)
		len = BUFFER_SIZE;

Admin message