Re: [PATCH 1/1] extcon: gpio: Add power resume support

[Barry Song]

2013/12/23 Chanwoo Choi <cw00.choi@xxxxxxxxxxx>:
> On 12/20/2013 05:09 PM, rjying wrote:
>> From: Rongjun Ying <rongjun.ying@xxxxxxx>
>>
>> After system resume, need send extcon uevent to userspace
>
> Why did extcon send uevent after wakeup from suspend?
>
> If extcon cable is attatched or detached on suspend state,
> Kernel can detect the interrupt about changed state of extcon.

irq controller has lost power in suspend, so there is no pending interrupt.
and HW will not pend any interrupt when we hotplug cable during sleep.

> So, kernel would execute proper operation about interrupt
> after wakeup from suspend state.

kernel only save/restore the register status of gpio, how could it
know whether there is a pending interrupt if the HW doesn't do it?

>
> I think it isn't necessary.
>
> Thanks,
> Chanwoo Choi
>
>>
>> Change-Id: I32a9e1c6646035f95765bba79a7acaccb8ce45a7
>>
>> Signed-off-by: Rongjun Ying <rongjun.ying@xxxxxxx>
>> ---
>>  drivers/extcon/extcon-gpio.c |   17 +++++++++++++++++
>>  1 files changed, 17 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/extcon/extcon-gpio.c b/drivers/extcon/extcon-gpio.c
>> index 7e0dff5..d916522 100644
>> --- a/drivers/extcon/extcon-gpio.c
>> +++ b/drivers/extcon/extcon-gpio.c
>> @@ -159,12 +159,29 @@ static int gpio_extcon_remove(struct platform_device *pdev)
>>       return 0;
>>  }
>>
>> +#ifdef CONFIG_PM_SLEEP
>> +static int gpio_extcon_resume(struct device *dev)
>> +{
>> +     struct gpio_extcon_data *extcon_data;
>> +
>> +     extcon_data = dev_get_drvdata(dev);
>> +     queue_delayed_work(system_power_efficient_wq, &extcon_data->work,
>> +                           extcon_data->debounce_jiffies);
>> +     return 0;
>> +}
>> +#endif
>> +
>> +static const struct dev_pm_ops gpio_extcon_pm_ops = {
>> +     SET_SYSTEM_SLEEP_PM_OPS(NULL, gpio_extcon_resume)
>> +};
>> +
>>  static struct platform_driver gpio_extcon_driver = {
>>       .probe          = gpio_extcon_probe,
>>       .remove         = gpio_extcon_remove,
>>       .driver         = {
>>               .name   = "extcon-gpio",
>>               .owner  = THIS_MODULE,
>> +             .pm = &gpio_extcon_pm_ops,
>>       },
>>  };
>>
>>
>

-barry
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