From: Felipe Balbi <balbi@ti.com>
To: Li Jun <b47624@freescale.com>
CC: Peter Chen <peter.chen@freescale.com>,
        Nathan Sullivan <nathan.sullivan@ni.com>, <gregkh@linuxfoundation.org>,
        <linux-usb@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH V4] usb: remove unnecessary CONFIG_PM dependency from USB_OTG
In-Reply-To: <20151201104932.GA23133@shlinux2>
References: <1446126743-31892-1-git-send-email-nathan.sullivan@ni.com> <8737wnnq3c.fsf@saruman.tx.rr.com> <20151104030056.GA20460@shlinux2> <87r3k6mngw.fsf@saruman.tx.rr.com> <20151201104932.GA23133@shlinux2>
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Date: Tue, 1 Dec 2015 08:25:55 -0600
Message-ID: <87fuzm1c0c.fsf@saruman.tx.rr.com>
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Hi Li,

Li Jun <b47624@freescale.com> writes:
>> > I am sorry I did not consider the legacy OTG design, this patch should
>> > be dropped.
>>=20
>> there is no "legacy" OTG design. OTG requires a bus suspend to enter
>> HNP, and that's achieved by stopping all transfers and avoid new URB
>> submission so usbcore can put the bus in suspend (by means of USB
>> autosuspend). If you're bypassing that in the OTG FSM thing, that needs
>> to be fixed ASAP as that makes it a lot harder for any generic changes
>> in usbcore to be validated. Specially when you consider not many will
>> have whatever special HW which, likely, doesn't even work with mainline
>> to validate a change.
>>=20
>> Please, make sure to fix that design so that HNP *always* goes through
>> the proper code path. If you have devices which would prevent HNP
>> because their class driver (host side driver) would never autosuspend,
>> fix that as well.
>>=20
>
> Hi Felipe
>
> I am going to fix this as you suggested, for those interface drivers which
> do not support autosuspend, should we
> - Fix its driver by enable autosuspend and adding suspend()&resume()? or
> - Unbind its interface before autosuspend the usb device?

IMO it's best if you could add proper autosuspend device to such drivers.

=2D-=20
balbi

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