From: Michael Walle <michael@xxxxxxxx> [ Upstream commit 8cac2f6eb8548245e6f8fb893fc7f2a714952654 ] 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> Link: https://lore.kernel.org/r/20210512141255.18277-10-michael@xxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- 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 777d54b593f8..109131b84945 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -1581,6 +1581,9 @@ 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; @@ -1610,6 +1613,9 @@ 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; -- 2.30.2
