linux-kernel - Re: [RESEND PATCH v3] mfd: tps65219: Add support for soft shutdown via sys-off API

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Message-ID: <0a0faa2b1f9ee02d86823ba0fe9faab7577ac426.camel@siemens.com>
Date: Fri, 15 Nov 2024 10:03:08 +0000
From: "Sverdlin, Alexander" <alexander.sverdlin@...mens.com>
To: "lee@...nel.org" <lee@...nel.org>, "tony@...mide.com" <tony@...mide.com>,
	"jneanne@...libre.com" <jneanne@...libre.com>
CC: "nm@...com" <nm@...com>, "msp@...libre.com" <msp@...libre.com>,
	"afd@...com" <afd@...com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "linux-omap@...r.kernel.org"
	<linux-omap@...r.kernel.org>, "khilman@...libre.com" <khilman@...libre.com>
Subject: Re: [RESEND PATCH v3] mfd: tps65219: Add support for soft shutdown
 via sys-off API

Hello all,

and sorry for spam,

On Fri, 2024-11-15 at 09:15 +0100, Alexander Sverdlin wrote:
> > Use new API for power-off mode support:
> > Link: https://lwn.net/Articles/894511/
> > Link: https://lore.kernel.org/all/7hfseqa7l0.fsf@baylibre.com/
> > 
> > sys-off API allows support of shutdown handler and restart handler.
> > 
> > Shutdown was not supported before that enhancement.
> > This is required for platform that are not using PSCI.
> > 
> > Test:
> > - restart:
> >   # reboot
> >   Default is cold reset:
> >   # cat /sys/kernel/reboot/mode
> >   Switch boot mode to warm reset:
> >   # echo warm > /sys/kernel/reboot/mode
> > - power-off:
> >   # halt
> > 
> > Tested on AM62-LP-SK board.
> > 
> > Signed-off-by: Jerome Neanne <jneanne@...libre.com>
> > Suggested-by: Andrew Davis <afd@...com>
> > Reviewed-by: Andrew Davis <afd@...com>
> > ---
> > 
> > Notes:
> >     Change-log v3 to v2
> >     v2: Link: https://lore.kernel.org/lkml/20230511122100.2225417-1-jneanne@baylibre.com/
> >     Lee Jones Review:
> >     nits: rm not needed line wraps and restore a cr deleted not related with the patch.
> >     
> >     Change-log v2 to v1
> >     v1: Link: https://lore.kernel.org/all/20230203140150.13071-1-jneanne@baylibre.com/
> >     Andrew Davis Review:
> >     - Use new helpers devm_register_restart_handler and devm_register_power_off_handler
> >     Vignesh Raghavendra:
> >     - Fix typo on board name in commit message
> > 
> >  drivers/mfd/tps65219.c | 38 ++++++++++++++++++++++++++++----------
> >  1 file changed, 28 insertions(+), 10 deletions(-)
> > 
> > diff --git a/drivers/mfd/tps65219.c b/drivers/mfd/tps65219.c
> > index 0e402fda206b..3d9164491e20 100644
> > --- a/drivers/mfd/tps65219.c
> > +++ b/drivers/mfd/tps65219.c
> > @@ -25,13 +25,21 @@ static int tps65219_cold_reset(struct tps65219 *tps)
> >  				  TPS65219_MFP_COLD_RESET_I2C_CTRL_MASK);
> >  }
> >  
> > -static int tps65219_restart(struct notifier_block *this,
> > -			    unsigned long reboot_mode, void *cmd)
> > +static int tps65219_soft_shutdown(struct tps65219 *tps)
> >  {
> > -	struct tps65219 *tps;
> > +	return regmap_update_bits(tps->regmap, TPS65219_REG_MFP_CTRL,
> > +				  TPS65219_MFP_I2C_OFF_REQ_MASK,
> > +				  TPS65219_MFP_I2C_OFF_REQ_MASK);
> 
> I suppose this is I2C access and is therefore a [potentially] sleeping call?
> Could this be an issue, see below...

I totally missed master_xfer_atomic = omap_i2c_xfer_polling in i2c-omap.c!
No issues here, I'm sorry!

> > +}
> >  
> > -	tps = container_of(this, struct tps65219, nb);
> > +static int tps65219_power_off_handler(struct sys_off_data *data)
> > +{
> > +	tps65219_soft_shutdown(data->cb_data);
> > +	return NOTIFY_DONE;
> > +}
> >  
> > +static int tps65219_restart(struct tps65219 *tps, unsigned long reboot_mode)
> > +{
> >  	if (reboot_mode == REBOOT_WARM)
> >  		tps65219_warm_reset(tps);
> >  	else
> > @@ -40,10 +48,11 @@ static int tps65219_restart(struct notifier_block *this,
> >  	return NOTIFY_DONE;
> >  }
> >  
> > -static struct notifier_block pmic_rst_restart_nb = {
> > -	.notifier_call = tps65219_restart,
> > -	.priority = 200,
> > -};
> > +static int tps65219_restart_handler(struct sys_off_data *data)
> > +{
> > +	tps65219_restart(data->cb_data, data->mode);
> > +	return NOTIFY_DONE;
> > +}
> >  
> >  static const struct resource tps65219_pwrbutton_resources[] = {
> >  	DEFINE_RES_IRQ_NAMED(TPS65219_INT_PB_FALLING_EDGE_DETECT, "falling"),
> > @@ -269,13 +278,22 @@ static int tps65219_probe(struct i2c_client *client)
> >  		}
> >  	}
> >  
> > -	tps->nb = pmic_rst_restart_nb;
> > -	ret = register_restart_handler(&tps->nb);
> > +	ret = devm_register_restart_handler(tps->dev,
> > +					    tps65219_restart_handler,
> > +					    tps);
> > +
> >  	if (ret) {
> >  		dev_err(tps->dev, "cannot register restart handler, %d\n", ret);
> >  		return ret;
> >  	}
> >  
> > +	ret = devm_register_power_off_handler(tps->dev,
> > +					      tps65219_power_off_handler,
> > +					      tps);
> 
> ... while this translates to
>         return devm_register_sys_off_handler(dev,
>                                              SYS_OFF_MODE_POWER_OFF,
> ... might this be an issue?
> 
> enum sys_off_mode {
> 
> []
>         /**
>          * @SYS_OFF_MODE_POWER_OFF:
>          *
>          * Handlers power-off system. Handlers are disallowed to sleep.
>          */
>         SYS_OFF_MODE_POWER_OFF,
> 
> 
> > +	if (ret) {
> > +		dev_err(tps->dev, "failed to register power-off handler: %d\n", ret);
> > +		return ret;
> > +	}
> >  	return 0;
> >  }
> 

-- 
Alexander Sverdlin
Siemens AG
www.siemens.com