Re: [PATCH v6 3/7] arm: Support restart through restart handler call chain

[Guenter Roeck]

On 08/09/2014 01:01 PM, Heiko Stübner wrote:
> Hi Guenter,
>
> Am Montag, 4. August 2014, 18:48:54 schrieb Guenter Roeck:
> > The kernel core now supports a restart handler call chain for system
> > restart functions.
> >
> > With this change, the arm_pm_restart callback is now optional, so check
> > if it is set before calling it. Only call the kernel restart handler
> > if arm_pm_restart is not set.
> >
> > Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> > Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>
> > Acked-by: Heiko Stuebner <heiko@xxxxxxxxx>
> > ---
> > v6: No change.
> > v5: Renamed restart function to do_kernel_restart
> > v4: No change.
> > v3: Use wrapper function to execute notifier call chain.
> > v2: Only call notifier call chain if arm_pm_restart is not set.
> >      Do not include linux/watchdog.h.
> >
> >   arch/arm/kernel/process.c | 5 ++++-
> >   1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
> > index 81ef686..84ca0d5 100644
> > --- a/arch/arm/kernel/process.c
> > +++ b/arch/arm/kernel/process.c
> > @@ -230,7 +230,10 @@ void machine_restart(char *cmd)
> >   	local_irq_disable();
> >   	smp_send_stop();
> >
> > -	arm_pm_restart(reboot_mode, cmd);
> > +	if (arm_pm_restart)
> > +		arm_pm_restart(reboot_mode, cmd);
> > +	else
> > +		do_kernel_restart(cmd);
> >
> >   	/* Give a grace period for failure to restart of 1s */
> >   	mdelay(1000);
>
> shouldn't you also get rid of
>
> 	void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd) = null_restart;
Yes. Looks like I'll need another revision.

Even worse, the current upstream code is somewhat broken and doesn't really
like the following instructions.
	drivers/watchdog/moxart_wdt.c:  arm_pm_restart = NULL;
	drivers/watchdog/sunxi_wdt.c:   arm_pm_restart = NULL;

Fortunately that code is only executed if those drivers are built as modules
and unloaded.

Guenter

> like a previous attempt at unifying the restart handling [0] did.
>
> Because when testing the current series on my Rockchip boards, there was
> always an arm_pm_restart defined ... namely the null_restart mentioned above.
> So do_kernel_restart is never reached until I disable the null_restart.
>
>
> Heiko
>
>
> [0] http://permalink.gmane.org/gmane.linux.ports.arm.kernel/277042
>
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