From: Michael Walle <michael@walle.cc> stable inclusion from stable-5.10.52 commit 4f3c807739e3c98160d6d8ca7e014b4110ba2a5b bugzilla: 175542 https://gitee.com/openeuler/kernel/issues/I4DTKU Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ 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@walle.cc> Link: https://lore.kernel.org/r/20210512141255.18277-10-michael@walle.cc Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Chen Jun <chenjun102@huawei.com> Acked-by: Weilong Chen <chenweilong@huawei.com> Signed-off-by: Chen Jun <chenjun102@huawei.com> --- 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 36f270261a57..2e74c88808db 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -1571,6 +1571,9 @@ 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; @@ -1600,6 +1603,9 @@ 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