linux-kernel - Re: [PATCH v2] serial: sh-sci: disable DMA for uart

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Date:   Tue, 14 May 2019 10:28:34 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     "George G. Davis" <george_davis@...tor.com>
Cc:     Eugeniu Rosca <erosca@...adit-jv.com>,
        Simon Horman <horms+renesas@...ge.net.au>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>,
        "open list:SERIAL DRIVERS" <linux-serial@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        Chris Brandt <chris.brandt@...esas.com>,
        Ulrich Hecht <ulrich.hecht+renesas@...il.com>,
        Andy Lowe <andy_lowe@...tor.com>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS 
        <devicetree@...r.kernel.org>, Magnus Damm <magnus.damm@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        stable <stable@...r.kernel.org>
Subject: Re: [PATCH v2] serial: sh-sci: disable DMA for uart_console

Hi George,

On Mon, May 13, 2019 at 5:48 PM George G. Davis <george_davis@...tor.com> 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/

I don't think this is an appropriate reference, as it points to a patch that
was never applied.

As the problem has basically existed forever, IMHO no Fixes tag
is needed.

> Reported-by: Michael Rodin <mrodin@...adit-jv.com>
> Tested-by: Eugeniu Rosca <erosca@...adit-jv.com>
> Reviewed-by: Simon Horman <horms+renesas@...ge.net.au>
> Reviewed-by: Wolfram Sang <wsa+renesas@...g-engineering.com>
> Cc: stable@...r.kernel.org
> Signed-off-by: George G. Davis <george_davis@...tor.com>
> ---
> v2: Clarify comment regarding DMA support on kernel console,
>     add {Tested,Reviewed}-by:, and Cc: linux-stable lines.

Thanks for the update!

Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds