linux-kernel - Re: [PATCH v5 3/6] kernel/reboot.c: export pm_power_off

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Message-ID: <1497969426.3177.14.camel@nxp.com>
Date:   Tue, 20 Jun 2017 17:37:06 +0300
From:   Leonard Crestez <leonard.crestez@....com>
To:     Oleksij Rempel <o.rempel@...gutronix.de>
CC:     Andrew Morton <akpm@...ux-foundation.org>,
        <devicetree@...r.kernel.org>,
        Fabio Estevam <fabio.estevam@....com>, <kernel@...gutronix.de>,
        Liam Girdwood <lgirdwood@...il.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-clk@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Mark Brown <broonie@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        "Michael Turquette" <mturquette@...libre.com>,
        Rob Herring <robh+dt@...nel.org>,
        Russell King <linux@...linux.org.uk>,
        Shawn Guo <shawnguo@...nel.org>,
        Stephen Boyd <sboyd@...eaurora.org>
Subject: Re: [PATCH v5 3/6] kernel/reboot.c: export pm_power_off_prepare

On Tue, 2017-06-20 at 07:01 +0200, Oleksij Rempel wrote:
> 
> On 19.06.2017 13:35, Leonard Crestez wrote:
> > 
> > On Mon, 2017-06-19 at 07:02 +0200, Oleksij Rempel wrote:
> > > 
> > > Export pm_power_off_prepare. It is needed to implement power off on
> > > Freescale/NXP iMX6 based boards with external power management
> > > integrated circuit (PMIC).
> > > 
> > > Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
> > > ---
> > >  kernel/reboot.c | 1 +
> > >  1 file changed, 1 insertion(+)
> > > 
> > > diff --git a/kernel/reboot.c b/kernel/reboot.c
> > > index bd30a973fe94..a6903bf772c7 100644
> > > --- a/kernel/reboot.c
> > > +++ b/kernel/reboot.c
> > > @@ -49,6 +49,7 @@ int reboot_force;
> > >   */
> > > 
> > >  void (*pm_power_off_prepare)(void);
> > > +EXPORT_SYMBOL(pm_power_off_prepare);
> > > 
> > Could you register a reboot notifier in the pfuze driver instead? Right
> > now the only user of pm_power_off_prepare is ACPI so this alternative
> > seems less intrusive.
> hm... in this case i will need to make sure that reboot handler is not 
> executed on reboot. This will make code looks strange. Which is opposite 
> of your comment in other email about strange standby code for power off :)
> Should i really do this?

A reboot handler receives a parameter to differentiate between reboot
and shutdown so it would be easy. Isn't it preferable to use an
existing mechanism instead of exporting a new symbol?

But maybe somebody else will Ack this, I don't particularly insist on
changing this.

--
Regards,
Leonard