linux-kernel - Re: [PATCH v3 3/3] usb: phy: hold wakeupsource when USB is enumerated in peripheral mode

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Message-ID: <CA+RfmHZRqMwiSAZ7kpn+0_8a+25O+hRKxGJuK6im6fX0dzB8Nw@mail.gmail.com>
Date:	Mon, 1 Dec 2014 11:09:48 +0530
From:	Kiran Raparthy <kiran.kumar@...aro.org>
To:	Felipe Balbi <balbi@...com>
Cc:	Peter Chen <Peter.Chen@...escale.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	Android Kernel Team <kernel-team@...roid.com>,
	John Stultz <john.stultz@...aro.org>,
	Sumit Semwal <sumit.semwal@...aro.org>,
	Arve Hjønnevåg <arve@...roid.com>,
	Benoit Goby <benoit@...roid.com>,
	Todd Poynor <toddpoynor@...gle.com>
Subject: Re: [PATCH v3 3/3] usb: phy: hold wakeupsource when USB is enumerated
 in peripheral mode

Hi Felipe,

On 25 November 2014 at 20:15, Felipe Balbi <balbi@...com> wrote:
> On Tue, Nov 25, 2014 at 07:06:18AM +0000, Peter Chen wrote:
>>
>> >
>> > usb: phy: hold wakeupsource when USB is enumerated in peripheral mode
>> >
>> > Some systems require a mechanism to prevent system to enter into suspend
>> > state when USB is connected and enumerated in peripheral mode.
>> >
>> > This patch provides an interface to hold a wakeupsource to prevent suspend.
>> > PHY drivers can use this interface when USB is connected and enumerated in
>> > peripheral mode.
>> >
>> > A timed wakeupsource is temporarily held on USB disconnect events, to allow
>> > the rest of the system to react to the USB disconnection (dropping host
>> > sessions, updating charger status, etc.) prior to re-allowing suspend.
>> >
>>
>> Hi Kiran & Felipe,
>>
>> Just two questions for this series
>>
>> - Will it be the default behavior for all peripheral drivers?
>> - If the peripheral driver's PHY driver does not vbus event, how to
>> support it?
>> For example, chipidea udc driver has its vbus interface at its
>> controller register.
>
> hmm, good point. Since it's so late, I'll just go ahead and drop
> $subject from v3.20. Let's delay only $subject to v3.20 merge window so
> we have some more time to discuss these details.

I am just curious to know/understand why this feature needs to be
default behavior for all peripheral drivers?
If this needs to be default behavior, could you please suggest any
alternate plan/design for this feature so that i can incorporate them
in new patch.
Regards,
Kiran

>
> cheers
>
> --
> balbi
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