[RFC v4 00/26] Fix watchdog on Renesas R-Car Gen2 and RZ/G1

[Geert Uytterhoeven]

Hi Fabrizio,

On Wed, Jan 31, 2018 at 7:24 PM, Fabrizio Castro
<fabrizio.castro at bp.renesas.com> wrote:
> the forth version of this series aims at consolidating the watchdog fix.
> There is a discussion still in progress about the changes to the
> watchdog driver, please see the following for more information:
> https://patchwork.kernel.org/patch/10192435/
>
> It doesn't look like leaving the restart handler in for Gen3 is going
> to do any harm (but it may be unwelcome), perhaps esplicitly setting
> its priority to a medium level (128) will help its adoption on Gen3
> as well? This is what this particular version is proposing.
>
> Also, although the latest implmentation of the reset vector hasn't
> raised any problem so far, it hasn't received any feedback either.
> Please do look into it to espose problems and weaknesses (if any).
>
> Finally, it would be great if someone could test this patch set on his
> Gen2/Gen3/RZ/G1 board, and it would be awesome if that board was a
> Lager with all of the cores enabled and working at the same time ;-)

I applied your series, made the following change:

--- a/arch/arm/boot/dts/r8a7791-koelsch.dts
+++ b/arch/arm/boot/dts/r8a7791-koelsch.dts
@@ -499,6 +499,11 @@
        status = "okay";
 };

+&rwdt {
+       timeout-sec = <5>;
+       status = "okay";
+};
+
 &sata0 {
        status = "okay";
 };

and tried it on koelsch. Unfortunately it hangs:

    # cat > /dev/watchdog
    [wait 5s]
    [hang]

However, it does work when booted with maxcpus=1, or when built with
CONFIG_SMP=n.

It also works when offlining CPU1 first:

    # echo 0 > /sys/devices/system/cpu/cpu1/online
    #cat > /dev/watchdog
    [wait 5s]
    [reboot]

It does not work when offlining CPU0 first.

This is on r8a7791 ES1.0.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-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