linux-kernel - Re: [PATCH v2 2/2] Revert "usb: dwc3: Don't switch OTG -> peripheral if extcon is present"

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Message-ID: <20221006021204.hz7iteao65dgsev6@synopsys.com>
Date:   Thu, 6 Oct 2022 02:12:20 +0000
From:   Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To:     Ferry Toth <fntoth@...il.com>
CC:     Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andrey Smirnov <andrew.smirnov@...il.com>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Felipe Balbi <balbi@...nel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] Revert "usb: dwc3: Don't switch OTG -> peripheral
 if extcon is present"

On Wed, Oct 05, 2022, Ferry Toth wrote:
> Hi,
> 
>     Thanks!
> 
>     Does the failure only happen the first time host is initialized? Or can
>     it recover after switching to device then back to host mode?
> 
> I can switch back and forth and device mode works each time, host mode remains
> dead.

Ok.

> 
>     Probably the failure happens if some step(s) in dwc3_core_init() hasn't
>     completed.
> 
>     tusb1210 is a phy driver right? The issue is probably because we didn't
>     initialize the phy yet. So, I suspect placing dwc3_get_extcon() after
>     initializing the phy will probably solve the dependency problem.
> 
>     You can try something for yourself or I can provide something to test
>     later if you don't mind (maybe next week if it's ok).
> 
> Yes, the code move I mentioned above "moves dwc3_get_extcon() until after
> dwc3_core_init() but just before dwc3_core_init_mode(). AFAIU initially
> dwc3_get_extcon() was called from within dwc3_core_init_mode() but only for
> case USB_DR_MODE_OTG. So with this change order of events is more or less
> unchanged" solves the issue.
> 

I saw the experiment you did from the link you provided. We want to also
confirm exactly which step in dwc3_core_init() was needed.

Thanks,
Thinh