From: Haavard Skinnemoen In atmel_spi_next_xfer, xfer can be NULL because the next transfer may already have been submitted to the PDC (using DMA chaining). This can cause an oops, since the debug message assumed it was never null. The fix changes how those debug messages are issued, ensuring that one is issued each time a transfer is started instead of once per call. Also, properly indent the "can this transfer be chained" test so it's not hidden as if it were non-conditional code. Signed-off-by: Haavard Skinnemoen Signed-off-by: David Brownell Signed-off-by: Andrew Morton --- drivers/spi/atmel_spi.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff -puN drivers/spi/atmel_spi.c~atmel_spi-fix-dmachain-oops-with-debug-enabled drivers/spi/atmel_spi.c --- a/drivers/spi/atmel_spi.c~atmel_spi-fix-dmachain-oops-with-debug-enabled +++ a/drivers/spi/atmel_spi.c @@ -198,6 +198,11 @@ static void atmel_spi_next_xfer(struct s len >>= 1; spi_writel(as, RCR, len); spi_writel(as, TCR, len); + + dev_dbg(&msg->spi->dev, + " start xfer %p: len %u tx %p/%08x rx %p/%08x\n", + xfer, xfer->len, xfer->tx_buf, xfer->tx_dma, + xfer->rx_buf, xfer->rx_dma); } else { xfer = as->next_transfer; remaining = as->next_remaining_bytes; @@ -208,8 +213,8 @@ static void atmel_spi_next_xfer(struct s if (remaining > 0) len = remaining; - else if (!atmel_spi_xfer_is_last(msg, xfer) && - atmel_spi_xfer_can_be_chained(xfer)) { + else if (!atmel_spi_xfer_is_last(msg, xfer) + && atmel_spi_xfer_can_be_chained(xfer)) { xfer = list_entry(xfer->transfer_list.next, struct spi_transfer, transfer_list); len = xfer->len; @@ -230,6 +235,11 @@ static void atmel_spi_next_xfer(struct s len >>= 1; spi_writel(as, RNCR, len); spi_writel(as, TNCR, len); + + dev_dbg(&msg->spi->dev, + " next xfer %p: len %u tx %p/%08x rx %p/%08x\n", + xfer, xfer->len, xfer->tx_buf, xfer->tx_dma, + xfer->rx_buf, xfer->rx_dma); } else { spi_writel(as, RNCR, 0); spi_writel(as, TNCR, 0); @@ -246,12 +256,6 @@ static void atmel_spi_next_xfer(struct s * It should be doable, though. Just not now... */ spi_writel(as, IER, SPI_BIT(ENDRX) | SPI_BIT(OVRES)); - - dev_dbg(&msg->spi->dev, - " start xfer %p: len %u tx %p/%08x rx %p/%08x imr %03x\n", - xfer, xfer->len, xfer->tx_buf, xfer->tx_dma, - xfer->rx_buf, xfer->rx_dma, spi_readl(as, IMR)); - spi_writel(as, PTCR, SPI_BIT(TXTEN) | SPI_BIT(RXTEN)); } _