From: "George G. Davis" <george_davis@mentor.com>
To: Eugeniu Rosca <erosca@de.adit-jv.com>
Cc: "George G. Davis" <ggdavisiv@gmail.com>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jiri Slaby <jslaby@suse.com>,
"open list:SERIAL DRIVERS" <linux-serial@vger.kernel.org>,
open list <linux-kernel@vger.kernel.org>,
Simon Horman <horms+renesas@verge.net.au>,
Chris Brandt <chris.brandt@renesas.com>,
Wolfram Sang <wsa+renesas@sang-engineering.com>,
Ulrich Hecht <ulrich.hecht+renesas@gmail.com>,
Andy Lowe <andy_lowe@mentor.com>,
Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS
<devicetree@vger.kernel.org>, Magnus Damm <magnus.damm@gmail.com>,
Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Eugeniu Rosca <roscaeugeniu@gmail.com>
Subject: Re: [PATCH] serial: sh-sci: disable DMA for uart_console
Date: Fri, 10 May 2019 14:38:47 -0400 [thread overview]
Message-ID: <20190510183847.GB28648@mam-gdavis-lt> (raw)
In-Reply-To: <20190510171021.GA22691@vmlxhi-102.adit-jv.com>
Hello Eugeniu,
On Fri, May 10, 2019 at 07:10:21PM +0200, Eugeniu Rosca wrote:
> Hi George,
>
> I am able to reproduce the SCIF2 console freeze described in the
> referenced patchwork link using M3-ES1.1-Salvator-XS and recent
> v5.1-9573-gb970afcfcabd kernel.
>
> I confirm the behavior is healed with this patch. Thanks!
> Hope to see it accepted soon, since it fixes a super annoying
> console breakage every fourth boot or so on lots of R-Car3 targets.
>
> Tested-by: Eugeniu Rosca <erosca@de.adit-jv.com>
Thanks for testing.
Also note, for the record, that the problem is not limited to SCIF2, e.g. try
setting console=ttySC<n> wheren <n> is not SCIF2 on any other board which
includes support for other serial ports, e.g. r8a7795-salvator-x, and you will
observe the same problem on other SCIF ports too. It's just a concidence that
most boards use SCIF2 as the default serial console where the console hangs
(resolved by this patch) have been observed on multiple boards.
>
> 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@de.adit-jv.com>
> > Cc: Eugeniu Rosca <erosca@de.adit-jv.com>
> > Signed-off-by: George G. Davis <george_davis@mentor.com>
> > ---
> > 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 */
> > +
> > if (!port->dev->of_node)
> > return;
> >
> > --
> > 2.7.4
> >
>
> --
> Best Regards,
> Eugeniu.
--
Regards,
George
next prev parent reply other threads:[~2019-05-10 18:39 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-04 0:42 [PATCH 0/6] Zap SCIF2 DMA configuration in R-Car Gen3 DTS Eugeniu Rosca
2019-05-04 0:42 ` [PATCH 1/6] serial: sh-sci: Reveal ptrval in dev_dbg Eugeniu Rosca
2019-05-06 13:47 ` Simon Horman
2019-05-06 15:24 ` Eugeniu Rosca
2019-05-06 16:46 ` Geert Uytterhoeven
2019-05-06 17:12 ` Eugeniu Rosca
2019-05-04 0:42 ` [PATCH 2/6] Revert "arm64: dts: renesas: r8a7796: Enable DMA for SCIF2" Eugeniu Rosca
2019-05-06 10:02 ` Geert Uytterhoeven
2019-05-06 19:42 ` Eugeniu Rosca
[not found] ` <1557413011-1662-1-git-send-email-george_davis@mentor.com>
2019-05-10 17:10 ` [PATCH] serial: sh-sci: disable DMA for uart_console Eugeniu Rosca
2019-05-10 18:38 ` George G. Davis [this message]
2019-05-13 10:28 ` Eugeniu Rosca
2019-05-13 11:13 ` Geert Uytterhoeven
2019-05-13 11:42 ` Simon Horman
2019-05-13 13:51 ` Wolfram Sang
2019-05-13 15:43 ` George G. Davis
2019-05-20 2:18 ` [PATCH 2/6] Revert "arm64: dts: renesas: r8a7796: Enable DMA for SCIF2" Yoshihiro Shimoda
2019-05-20 7:37 ` Geert Uytterhoeven
2019-05-20 9:52 ` Yoshihiro Shimoda
2019-05-04 0:42 ` [PATCH 3/6] arm64: dts: renesas: r8a7795: zap dma configuration in scif2 Eugeniu Rosca
2019-05-04 0:42 ` [PATCH 4/6] Revert "arm64: dts: renesas: r8a77965: Enable DMA for SCIF2" Eugeniu Rosca
2019-05-04 0:42 ` [PATCH 5/6] Revert "arm64: dts: renesas: r8a77990: " Eugeniu Rosca
2019-05-04 0:42 ` [PATCH 6/6] Revert "arm64: dts: renesas: r8a77995: add " Eugeniu Rosca
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