[PATCH 1/2] gpio-vbus: support disabling D+ pullup on suspend

[dbaryshkov@gmail.com (Dmitry Eremin-Solenikov)]

On 6/22/11, Felipe Balbi <balbi@ti.com> wrote:
> Hi,
>
> On Wed, Jun 22, 2011 at 04:20:16PM +0400, Dmitry Eremin-Solenikov wrote:
>> Some platforms would like to disable D+ pullup on suspend, to drain as
>> low power, as possible. E.g. this was requested by mioa701 board
>> maintainers.
>
> I think this makes sense to many platforms, but by doing so, you would
> loose connection to the Host PC, so you need to make sure your device
> isn't been used before you go down this road.

I've thought about this. Should UDC driver should somehow call into OTG
layer on suspend? My understanding is that otg_set_suspend isn't the call
that should be done here, is it true?

My idea was that board can ask for D+ disabling, knowing itself the behaviour
of the platform driver on suspend (e.g. PXA27x does disable UDC on suspend,
but I dunno what effect this will cause on Host PC).

>> Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
>> ---
>>  drivers/usb/otg/gpio_vbus.c   |   32 ++++++++++++++++++++++++++++++++
>>  include/linux/usb/gpio_vbus.h |    1 +
>>  2 files changed, 33 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/usb/otg/gpio_vbus.c b/drivers/usb/otg/gpio_vbus.c
>> index 52733d9..44527bd 100644
>> --- a/drivers/usb/otg/gpio_vbus.c
>> +++ b/drivers/usb/otg/gpio_vbus.c
>> @@ -327,6 +327,34 @@ static int __exit gpio_vbus_remove(struct
>> platform_device *pdev)
>>  	return 0;
>>  }
>>
>> +#ifdef CONFIG_PM
>> +static int gpio_vbus_suspend(struct platform_device *pdev, pm_message_t
>> state)
>> +{
>> +	struct gpio_vbus_data *gpio_vbus = platform_get_drvdata(pdev);
>> +	struct gpio_vbus_mach_info *pdata = gpio_vbus->dev->platform_data;
>> +
>> +	if (gpio_vbus->otg.gadget && pdata->disconnect_on_suspend) {
>> +		/* optionally disable D+ pullup */
>> +		if (gpio_is_valid(pdata->gpio_pullup))
>> +			gpio_set_value(pdata->gpio_pullup,
>> +					pdata->gpio_pullup_inverted);
>> +
>> +		set_vbus_draw(gpio_vbus, 0);
>> +	}
>> +	return 0;
>> +}
>> +
>> +static int gpio_vbus_resume(struct platform_device *pdev)
>> +{
>> +	struct gpio_vbus_data *gpio_vbus = platform_get_drvdata(pdev);
>> +
>> +	if (gpio_vbus->otg.gadget)
>> +		schedule_work(&gpio_vbus->work);
>> +
>> +	return 0;
>> +}
>
> actually, the correct way would be to use dev_pm_ops.

Could I use SIMPLE_DEV_PM_OPS here?

>
>> +#endif
>> +
>>  /* NOTE:  the gpio-vbus device may *NOT* be hotplugged */
>>
>>  MODULE_ALIAS("platform:gpio-vbus");
>> @@ -337,6 +365,10 @@ static struct platform_driver gpio_vbus_driver = {
>>  		.owner = THIS_MODULE,
>>  	},
>>  	.remove  = __exit_p(gpio_vbus_remove),
>> +#ifdef CONFIG_PM
>> +	.suspend	= gpio_vbus_suspend,
>> +	.resume		= gpio_vbus_resume
>> +#endif
>
> also, avoid the ifdef on the driver structure.

Ack. Was just C&P from gpio-vbus, but it's not an excuse
to follow bad style.


-- 
With best wishes
Dmitry