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

Dmitry Eremin-Solenikov dbaryshkov at gmail.com
Wed Jun 22 10:15:17 EDT 2011

On 6/22/11, Felipe Balbi <balbi at ti.com> wrote:
> Hi,
> On Wed, Jun 22, 2011 at 05:52:18PM +0400, Dmitry Eremin-Solenikov wrote:
>> On 6/22/11, Felipe Balbi <balbi at 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).
> Host PC will only see the device disconnecting. So, what happens if the
> user has mounted file systems when you decide to go into suspend ?

What happens if user has mounted filesystems when I decide to pull out
the cable?
I agree with you generally, but I'd like to hear any suggestions.

With best wishes

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