linux-kernel - Re: [PATCH v4] usb: dwc3: Don't switch OTG -> peripheral if extcon is present

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Message-ID: <b533e337-3d5f-c514-f0d1-e4684e3a5d64@gmail.com>
Date:   Thu, 22 Sep 2022 16:30:09 +0200
From:   Ferry Toth <fntoth@...il.com>
To:     Andy Shevchenko <andriy.shevchenko@...el.com>,
        Andrey Smirnov <andrew.smirnov@...il.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Felipe Balbi <balbi@...nel.org>,
        Thinh Nguyen <thinhn@...opsys.com>, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Thinh Nguyen <Thinh.Nguyen@...opsys.com>
Subject: Re: [PATCH v4] usb: dwc3: Don't switch OTG -> peripheral if extcon is
 present

Hi,

Resending this due to html reject, sorry.

On 22-09-2022 12:08, Andy Shevchenko wrote:
> On Sun, Apr 03, 2022 at 09:49:07AM -0700, Andrey Smirnov wrote:
>> If the extcon device exists, get the mode from the extcon device. If
>> the controller is DRD and the driver is unable to determine the mode,
>> only then default the dr_mode to USB_DR_MODE_PERIPHERAL.
> According to Ferry (Cc'ed) this broke Intel Merrifield platform. Ferry, can you
> share bisect log?

I can but not right now. But what I did was bisect between 5.18.0 (good) 
and 5.19.0 (bad) then when I got near the culprit (~20 remaining) based 
on the commit message I tried 0f01017191384e3962fa31520a9fd9846c3d352f 
"usb: dwc3: Don't switch OTG -> peripheral if extcon is present" (bad) 
and commit before that (good).

The effect of the patch is that on Merrifield (I tested with Intel 
Edison Arduino board which has a HW switch to select between host and 
device mode) device mode works but in host mode USB is completely not 
working.

Currently on host mode - when working - superfluous error messages from 
tusb1210 appear. When host mode is not working there are no tusb1210 
messages in the logs / on the console at all. Seemingly tusb1210 is not 
probed, which points in the direction of a relation to extcon.

> Taking into account the late cycle, I would like to revert the change. And
> Ferry and I would help to test any other (non-regressive) approach).
>
I have not yet tested if a simple revert fixes the problem but will tonight.

I would be happy to test other approaches too.