From: George G. Davis <[email protected]>
commit 099506cbbc79c0bd52b19cb6b930f256dabc3950 upstream.
As noted in commit 84b40e3b57ee ("serial: 8250: omap: Disable DMA for
console UART"), UART console lines use low-level PIO only access functions
which will conflict with use of the line when DMA is enabled, e.g. when
the console line is also used for systemd messages. So disable DMA
support for UART console lines.
Reported-by: Michael Rodin <[email protected]>
Link: https://patchwork.kernel.org/patch/10929511/
Tested-by: Eugeniu Rosca <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Reviewed-by: Wolfram Sang <[email protected]>
Reviewed-by: Geert Uytterhoeven <[email protected]>
Cc: [email protected]
Signed-off-by: George G. Davis <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/tty/serial/sh-sci.c | 7 +++++++
1 file changed, 7 insertions(+)
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -1479,6 +1479,13 @@ static void sci_request_dma(struct uart_
dev_dbg(port->dev, "%s: port %d\n", __func__, port->line);
+ /*
+ * DMA on console may interfere with Kernel log messages which use
+ * plain putchar(). So, simply don't use it with a console.
+ */
+ if (uart_console(port))
+ return;
+
if (!port->dev->of_node)
return;
