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

Guenter Roeck
2014-11-10T14:09:27Z

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