linux-kernel - Re: [PATCH] usb: hcd: add OTG ID signal sensing

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Message-ID: <54916A82.4010105@cogentembedded.com>
Date:	Wed, 17 Dec 2014 14:35:30 +0300
From:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:	Peter Chen <Peter.Chen@...escale.com>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>
CC:	"linux-sh@...r.kernel.org" <linux-sh@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] usb: hcd: add OTG ID signal sensing

Hello.

On 12/17/2014 5:08 AM, Peter Chen wrote:

>> On the Renesas R8A7791 SoC based boards there's MAX3355 USB OTG chip and
>> mini-AB USB connector corresponding to USB port 0 driven either by EHCI/OHCI
>> or  Renesas USBHS gadget controller. And we'd like the  host/gadget drivers to
>> work based on the cable type connected. An 'extcon' driver for MAX3355 has
>> been written, so we only need to bind  to it via device tree which I'm doing in
>> this patch.

>> I wasn't able to find a solution better than checking the cable type at the host
>> driver probe time and refusing to drive a host if B-cable is connected.

> You may need a dual-role/otg driver to do it, which can enable host/device function
> according to ID pin.

    It would have been too good if I had a dual-role controller. :-)
    But I have what I have. IIUC, such configuration (OHCI and UDC sharing a 
USB port) has been used on OMAP1.

WBR, Sergei

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