linux-kernel - Re: [PATCH/RFT 07/12] USB: ohci-da8xx: Request gpios and handle interrupt in the driver

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Date:   Wed, 12 Oct 2016 18:31:18 -0500
From:   David Lechner <david@...hnology.com>
To:     Axel Haslam <ahaslam@...libre.com>
Cc:     Greg KH <gregkh@...uxfoundation.org>, robh+dt@...nel.org,
        Sekhar Nori <nsekhar@...com>,
        Alan Stern <stern@...land.harvard.edu>,
        Kevin Hilman <khilman@...libre.com>,
        Sergei Shtylyov <sshtylyov@...mvista.com>,
        linux-usb@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH/RFT 07/12] USB: ohci-da8xx: Request gpios and handle
 interrupt in the driver

On 10/12/2016 10:01 AM, Axel Haslam wrote:
> I  agree that we should use a regulator for the vbus power.
> i will make that change.  However, im not so sure about using the
> regulator for the overcurrent handling. There seems to be no other
> driver doing this, and as you mention, we would need to change the regulator
> framework, which might not be justifiable. I think there is not another way
> to handle the over current notification other than powering the port off.

The regulator framework has REGULATOR_EVENT_OVER_CURRENT already. 
Perhaps this could be of some use? For example you could extend the 
existing gpio-regulator driver with an optional overcurrent gpio pin.


>
> how about using regulator for vbus, but keeping gpio for overcurrent
> notifications?

See the suggestion above about extending the gpio-regulator driver.


> For the usersapce handling you describe above, maybe we should be able to
> listen for an usb overcurrent uevent in userspace? it seems this
> question was asked
> a couple of years back[1], but im not sure what the conclusion was. In any case,
> we could have DT and non-DT based ohci-da8xx working,
> And could work on a uevent notification for the scenario you describe
> above which
> i think is not specific to the ohci-da8xx.
>
> [1]http://linux-usb.vger.kernel.narkive.com/SjcUB5hk/how-best-to-get-over-current-notification-to-user-application

Thanks for the link. Too bad it seems nothing ever became of this. I 
guess it will be up to me to bring up the discussion again if I really 
want it.