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

From: Ferry Toth <fntoth@gmail.com>
To: Andrey Smirnov <andrew.smirnov@gmail.com>,
	Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Felipe Balbi <balbi@kernel.org>,
	"stable@vger.kernel.org" <stable@vger.kernel.org>
Subject: Re: [PATCH v2 2/2] Revert "usb: dwc3: Don't switch OTG -> peripheral if extcon is present"
Date: Wed, 5 Oct 2022 10:45:03 +0200	[thread overview]
Message-ID: <53ca04e3-ee6f-1c4d-3a08-7b5d9dd0d629@gmail.com> (raw)
In-Reply-To: <CAHQ1cqG9-SDM4_zUfCvxP7XD-U+PPOWqWDBFKU73ecomDpt9Jw@mail.gmail.com>

Hi

On 05-10-2022 04:39, Andrey Smirnov wrote:
> On Tue, Oct 4, 2022 at 7:12 PM Thinh Nguyen<Thinh.Nguyen@synopsys.com>  wrote:
>> On Tue, Oct 04, 2022, Ferry Toth wrote:
>>> Hi
>>>
>>> Op 04-10-2022 om 10:28 schreef Andy Shevchenko:
>>>> On Mon, Oct 03, 2022 at 09:57:35PM +0000, Thinh Nguyen wrote:
>>>>> On Tue, Sep 27, 2022, Andy Shevchenko wrote:
>>>>>> This reverts commit 0f01017191384e3962fa31520a9fd9846c3d352f.
>>>>>>
>>>>>> As pointed out by Ferry this breaks Dual Role support on
>>>>>> Intel Merrifield platforms.
>>>>> Can you provide more info than this (any debug info/description)? It
>>>>> will be difficult to come back to fix with just this to go on. The
>>>>> reverted patch was needed to fix a different issue.
>>> On Merrifield we have a switch with extcon driver to switch between host and
>>> device mode. Now with commit 0f01017, device mode works. In host mode the
>>> root hub appears, but no devices appear. In the logs there are no messages
>>> from tusb1210, but there should be because lately there normally are
>>> (harmless) error messages. Nothing in the logs point in the direction of
>>> tusb1210 not being probed.
>>>
>>> The discussion is here:https://urldefense.com/v3/__https://lkml.org/lkml/2022/9/24/237__;!!A4F2R9G_pg!avfDjiGwi8xu0grHYrQQTZEEUnmaKu82xxdty0ZltxyU8BkoFD6AMq4a-7STYiKxNQpdYXgP1QG_IZbroEM$
>>>
>>> I tried moving some code as suggested without result:https://urldefense.com/v3/__https://lkml.org/lkml/2022/9/24/434__;!!A4F2R9G_pg!avfDjiGwi8xu0grHYrQQTZEEUnmaKu82xxdty0ZltxyU8BkoFD6AMq4a-7STYiKxNQpdYXgP1QG_boaK8Qw$
>>>
>>> And with success:https://urldefense.com/v3/__https://lkml.org/lkml/2022/9/25/285__;!!A4F2R9G_pg!avfDjiGwi8xu0grHYrQQTZEEUnmaKu82xxdty0ZltxyU8BkoFD6AMq4a-7STYiKxNQpdYXgP1QG_MbbbZII$
>>>
>>> So, as Andrey Smirnov writes "I think we'd want to figure out why the
>>> ordering is important if we want to justify the above fix."
>>>
>>>> It's already applied, but Ferry probably can provide more info if you describe
>>>> step-by-step instructions. (I'm still unable to test this particular type of
>>>> features since remove access is always in host mode.)
>>>>
>>> I'd be happy to test.
>> 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?
>>
>> 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).
> FWIW, I just got the same HW Ferry has last week and am planning to
> work on this over the weekend.
I can help you setup, we have binary images available on github as well 
as Yocto recipies to build them.