Re: [PATCH v5 18/48] mfd: twl4030-power: Register with kernel power-off handler

[Guenter Roeck]

On 11/10/2014 12:46 AM, Pavel Machek wrote:
> Hi!
>
> > @@ -611,7 +611,7 @@ twl4030_power_configure_resources(const struct twl4030_power_data *pdata)
> >    * After a successful execution, TWL shuts down the power to the SoC
> >    * and all peripherals connected to it.
> >    */
> > -void twl4030_power_off(void)
> > +static void twl4030_power_off(struct power_off_handler_block *this)
> >   {
> >   	int err;
> >
> > @@ -621,6 +621,11 @@ void twl4030_power_off(void)
> >   		pr_err("TWL4030 Unable to power off\n");
> >   }
> >
> > +static struct power_off_handler_block twl4030_power_off_hb = {
> > +	.handler = twl4030_power_off,
> > +	.priority = POWER_OFF_PRIORITY_LOW,
> > +};
> > +
> >   static bool twl4030_power_use_poweroff(const struct twl4030_power_data *pdata,
> >   					struct device_node *node)
> >   {
> > @@ -839,7 +844,9 @@ static int twl4030_power_probe(struct platform_device *pdev)
> >   	}
> >
> >   	/* Board has to be wired properly to use this feature */
> > -	if (twl4030_power_use_poweroff(pdata, node) && !pm_power_off) {
> > +	if (twl4030_power_use_poweroff(pdata, node)) {
> > +		int ret;
> > +
> >   		/* Default for SEQ_OFFSYNC is set, lets ensure this */
> >   		err = twl_i2c_read_u8(TWL_MODULE_PM_MASTER, &val,
> >   				      TWL4030_PM_MASTER_CFG_P123_TRANSITION);
> > @@ -856,7 +863,11 @@ static int twl4030_power_probe(struct platform_device *pdev)
> >   			}
> >   		}
> >
> > -		pm_power_off = twl4030_power_off;
> > +		ret = devm_register_power_off_handler(&pdev->dev,
> > +						      &twl4030_power_off_hb);
> > +		if (ret)
> > +			dev_warn(&pdev->dev,
> > +				 "Failed to register power-off handler\n");
> >   	}
>
> Could we get rid of the "struct power_off_handler_block" and guarantee
> that register_power_off never fails (or print message from the
> register_power_off...)? That way, your patch would be an cleanup.
>
> You could then add priorities if they turn out to be really
> neccessary, later...

Priorities are necessary. We had _that_ discussion before.
Priorities solve the problem where multiple handlers are installed,
either conditionally or unconditionally. If I take priorities away,
a substantial part of the patch set's value gets lost, and I might
as well drop it.

Guenter

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