Hello Wolfram,
On Mon, May 13, 2019 at 03:51:14PM +0200, Wolfram Sang wrote:
> On Thu, May 09, 2019 at 10:43:30AM -0400, George G. Davis wrote:
> > 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.
> >
> > Fixes: https://patchwork.kernel.org/patch/10929511/
> > Reported-by: Michael Rodin <mrodin@xxxxxxxxxxxxxx>
> > Cc: Eugeniu Rosca <erosca@xxxxxxxxxxxxxx>
> > Signed-off-by: George G. Davis <george_davis@xxxxxxxxxx>
> > ---
> > drivers/tty/serial/sh-sci.c | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
> > index 3cd139752d3f..885b56b1d4e4 100644
> > --- a/drivers/tty/serial/sh-sci.c
> > +++ b/drivers/tty/serial/sh-sci.c
> > @@ -1557,6 +1557,9 @@ static void sci_request_dma(struct uart_port *port)
> >
> > dev_dbg(port->dev, "%s: port %d\n", __func__, port->line);
> >
> > + if (uart_console(port))
> > + return; /* Cannot use DMA on console */
>
> Minor nit: maybe the comment can be made more specific?
>
> /*
> * DMA on console may interfere with Kernel log messages which use
> * plain putchar(). So, simply don't use it with a console.
> */
I'll submit v2 with the above recommended change.
Thanks!
> Other than that:
>
> Reviewed-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
>
> Much better than dropping the properties, as Geert noted.
--
Regards,
George
