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authorGeorge G. Davis <george_davis@mentor.com>2019-05-14 23:29:34 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-05-21 12:18:17 +0200
commit099506cbbc79c0bd52b19cb6b930f256dabc3950 (patch)
tree6f62ffb39a5a262fd15ec6541953bffea7ba991f /drivers
parent8178eeb3e8007d29b1e9dfd3c4d0f90de0f6ce55 (diff)
downloadlinux-099506cbbc79c0bd52b19cb6b930f256dabc3950.tar.bz2
serial: sh-sci: disable DMA for uart_console
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 <mrodin@de.adit-jv.com> Link: https://patchwork.kernel.org/patch/10929511/ Tested-by: Eugeniu Rosca <erosca@de.adit-jv.com> Reviewed-by: Simon Horman <horms+renesas@verge.net.au> Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be> Cc: stable@vger.kernel.org Signed-off-by: George G. Davis <george_davis@mentor.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/tty/serial/sh-sci.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 3cd139752d3f..abc705716aa0 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -1557,6 +1557,13 @@ static void sci_request_dma(struct uart_port *port)
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;