SYSRQ doesn't work with DMA. This is because there is no error indication whether a symbol had a framing error or not. Actually, this is not completely correct, there is a bit in the data register which is set in this case, but we'd have to read change the DMA access to 16 bit and we'd need to post process the data, thus make the DMA pointless in the first place. Signed-off-by: Michael Walle <michael@xxxxxxxx> --- Please note, that there is already sysrq/break support in the 8 bit version. But I think there is a race between the hardware DMA controller and the ISR in this driver. I'm not sure though and can't test it. Angelo, maybe you could test it, I'd presume with this patch you don't need the special handling in the ISR anymore. drivers/tty/serial/fsl_lpuart.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index 1ed019d91177..0185bb8b6000 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -1587,6 +1587,9 @@ static void lpuart_tx_dma_startup(struct lpuart_port *sport) u32 uartbaud; int ret; + if (uart_console(&sport->port)) + goto err; + if (!sport->dma_tx_chan) goto err; @@ -1616,6 +1619,9 @@ static void lpuart_rx_dma_startup(struct lpuart_port *sport) int ret; unsigned char cr3; + if (uart_console(&sport->port)) + goto err; + if (!sport->dma_rx_chan) goto err; -- 2.20.1
