if the DMA driver isn't loaded "on time" then we crash in the irq handler: | pch_uart 0000:02:0a.4: pch_request_dma:dma_request_channel FAILS(Tx) | BUG: unable to handle kernel NULL pointer dereference at (null) | IP: [<c0676ed9>] pch_uart_interrupt+0x739/0x940
Signed-off-by: Sebastian Andrzej Siewior <[email protected]> --- drivers/tty/serial/pch_uart.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/tty/serial/pch_uart.c b/drivers/tty/serial/pch_uart.c index 20e4c94..9b7cd40 100644 --- a/drivers/tty/serial/pch_uart.c +++ b/drivers/tty/serial/pch_uart.c @@ -1492,10 +1492,14 @@ static int pch_uart_verify_port(struct uart_port *port, __func__); return -EOPNOTSUPP; #endif - dev_info(priv->port.dev, "PCH UART : Use DMA Mode\n"); - if (!priv->use_dma) + if (!priv->use_dma) { pch_request_dma(port); - priv->use_dma = 1; + if (priv->chan_rx) + priv->use_dma = 1; + } + dev_info(priv->port.dev, "PCH UART: %s\n", + priv->use_dma ? + "Use DMA Mode" : "No DMA"); } return 0; -- 1.8.4.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
