From mboxrd@z Thu Jan  1 00:00:00 1970
From: stephen.boyd@linaro.org (Stephen Boyd)
Date: Wed, 29 Jun 2016 18:19:59 -0700
Subject: [PATCH 08/21] usb: chipidea: Kick OTG state machine for AVVIS
 with vbus extcon
In-Reply-To: <20160629030913.GC25236@shlinux2>
References: <20160626072838.28082-1-stephen.boyd@linaro.org>
 <20160626072838.28082-9-stephen.boyd@linaro.org>
 <20160629030913.GC25236@shlinux2>
Message-ID: <146724959973.16253.818114721999543873@sboyd-linaro>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

Quoting Peter Chen (2016-06-28 20:09:13)
> On Sun, Jun 26, 2016 at 12:28:25AM -0700, Stephen Boyd wrote:
> > Force the OTG state machine to go forward when we're using an
> > extcon for vbus detection. In this case, the controller may never
> > raise an interrupt for AVVIS, so we need to simulate the event by
> > toggling the appropriate OTG fsm bits and kicking the state
> > machine again.
> > 
> 
> Well, I think you may misunderstand the OTG FSM and dual-role.
> From my and Felipe's point, there are seldom users for USB FSM,
> there are only OTG FSM spec and related OTG certification.

Probably yes.

> 
> The OTG FSM needs related SoC support, the vbus will be off at
> several states, and the SRP should be supported by SoC.
> 
> By default, the dts needs below properties for disabling it if you
> choose otg fsm support at kernel configuration.
> 
> &usbotg1 {
>         vbus-supply = <&reg_usb_otg1_vbus>;
>         srp-disable;
>         hnp-disable;
>         adp-disable;
>         status = "okay";
> };
> 
> See Documentation/devicetree/bindings/usb/generic.txt.

Does this mean we should be setting all those properties if we're using
an extcon for vbus and id? I have noticed that vbus is powered off after
some time when no device is connected and we're in A_HOST state because
the timeout for a B device connection happens.