Re: [PATCH] Input: pm8941-pwrkey - respect reboot_mode for warm reset

[Shawn Guo <shawn.guo@linaro.org>]

Hi Luca,

On Sun, Jul 11, 2021 at 11:57:25AM +0200, Luca Weiss wrote:
> Hi Shawn,
> 
> On Dienstag, 29. Juni 2021 05:05:09 CEST Shawn Guo wrote:
> > On some devices, e.g. Sony Xperia M4 Aqua, warm reset is used to reboot
> > device into bootloader and recovery mode.  Instead of always doing hard
> > reset, add a check on reboot_mode for possible warm reset.
> > 
> > Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
> > ---
> >  drivers/input/misc/pm8941-pwrkey.c | 6 +++++-
> >  1 file changed, 5 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/input/misc/pm8941-pwrkey.c
> > b/drivers/input/misc/pm8941-pwrkey.c index cf8104454e74..9b14d6eb1918
> > 100644
> > --- a/drivers/input/misc/pm8941-pwrkey.c
> > +++ b/drivers/input/misc/pm8941-pwrkey.c
> > @@ -27,6 +27,7 @@
> >  #define PON_PS_HOLD_RST_CTL2		0x5b
> >  #define  PON_PS_HOLD_ENABLE		BIT(7)
> >  #define  PON_PS_HOLD_TYPE_MASK		0x0f
> > +#define  PON_PS_HOLD_TYPE_WARM_RESET	1
> >  #define  PON_PS_HOLD_TYPE_SHUTDOWN	4
> >  #define  PON_PS_HOLD_TYPE_HARD_RESET	7
> > 
> > @@ -93,7 +94,10 @@ static int pm8941_reboot_notify(struct notifier_block
> > *nb, break;
> >  	case SYS_RESTART:
> >  	default:
> > -		reset_type = PON_PS_HOLD_TYPE_HARD_RESET;
> > +		if (reboot_mode == REBOOT_WARM)
> 
> This doesn't compile with CONFIG_INPUT_PM8941_PWRKEY=m
> 
>  ERROR: modpost: "reboot_mode" [drivers/input/misc/pm8941-pwrkey.ko] undefined!

Thanks for the report!  I will add a patch to export the symbol.

> 
> Also just to clarify, this is supposed to trigger when rebooting with 
> LINUX_REBOOT_CMD_RESTART2 and adding an argument that way, right?

With either of the following two methods, 'reboot_mode' will be turned
into REBOOT_WARM.

- Boot kernel with 'reboot=warm' on cmdline

- Set warm mode via sysfs entry
  $ echo warm > /sys/kernel/reboot/mode

Shawn