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Message-ID: <644adb7b-0438-e37c-222c-71bf261369b0@gmail.com>
Date:   Tue, 11 Oct 2022 20:38:04 +0200
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Subject: Re: [PATCH v2 2/2] Revert "usb: dwc3: Don't switch OTG -> peripheral
 if extcon is present"
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To:     Andrey Smirnov <andrew.smirnov@gmail.com>
Cc:     Thinh Nguyen <Thinh.Nguyen@synopsys.com>,
        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>
References: <20220927155332.10762-1-andriy.shevchenko@linux.intel.com>
 <20220927155332.10762-3-andriy.shevchenko@linux.intel.com>
 <20221003215734.7l3cnb2zy57nrxkk@synopsys.com>
 <YzvusOI89ju9e5+0@smile.fi.intel.com>
 <a7724993-6c04-92c5-3a26-3aef6d29c9e3@gmail.com>
 <20221005021212.qwnbmq6p7t26c3a4@synopsys.com>
 <2886b82d-a1f6-d288-e8d1-edae54046b4f@gmail.com>
 <20221006021204.hz7iteao65dgsev6@synopsys.com>
 <d52cc102-6a4f-78e9-6176-b33e2813fd1d@gmail.com>
 <20221007021122.nnwmqc6sq43e5xbn@synopsys.com>
 <ade865f1-8ed5-a8e3-e441-cb7688c6d001@gmail.com>
 <CAHQ1cqGSmNSg73DzURrcP=a-cCd6KdVUtUmnonhP54vWVDmEhw@mail.gmail.com>
 <4e73bbb9-eae1-6a90-d716-c721a1eeced3@gmail.com>
 <7e9519c6-f65f-5f83-1d17-a3510103469f@gmail.com>
 <CAHQ1cqE5=j9i8uYvBwdNUK8TrX3Wxy7iUML6K+gBQx-KRtkS7w@mail.gmail.com>
From:   Ferry Toth <fntoth@gmail.com>
In-Reply-To: <CAHQ1cqE5=j9i8uYvBwdNUK8TrX3Wxy7iUML6K+gBQx-KRtkS7w@mail.gmail.com>
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Hi,

Op 10-10-2022 om 23:35 schreef Andrey Smirnov:
> On Mon, Oct 10, 2022 at 1:52 PM Ferry Toth <fntoth@gmail.com> wrote:
>>
>> Hi
>>
>> Op 10-10-2022 om 13:04 schreef Ferry Toth:
>>> Hi
>>>
>>> On 10-10-2022 07:02, Andrey Smirnov wrote:
>>>> On Fri, Oct 7, 2022 at 6:07 AM Ferry Toth <fntoth@gmail.com> wrote:
>>>>>
>>>>> On 07-10-2022 04:11, Thinh Nguyen wrote:
>>>>>> On Thu, Oct 06, 2022, Ferry Toth wrote:
>>>>>>> Hi
>>>>>>>
>>>>>>> On 06-10-2022 04:12, Thinh Nguyen wrote:
>>>>>>>> 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.
>>>>>>> Ok. I first tried the code move suggested by Andrey (didn't work).
>>>>>>> Then
>>>>>>> after reading the actual code I moved a bit further.
>>>>>>>
>>>>>>> This move was on top of -rc6 without any reverts. I did not make
>>>>>>> additional
>>>>>>> changes to dwc3_core_init()
>>>>>>>
>>>>>>> So current v6.0 has: dwc3_get_extcon - dwc3_get_dr_mode - ... -
>>>>>>> dwc3_core_init - .. - dwc3_core_init_mode (not working)
>>>>>>>
>>>>>>> I changed to: dwc3_get_dr_mode - dwc3_get_extcon - .. -
>>>>>>> dwc3_core_init - ..
>>>>>>> - dwc3_core_init_mode (no change)
>>>>>>>
>>>>>>> Then to: dwc3_get_dr_mode - .. - dwc3_core_init - .. -
>>>>>>> dwc3_get_extcon -
>>>>>>> dwc3_core_init_mode (works)
>>>>>>>
>>>>>>> .. are what I believe for this issue irrelevant calls to
>>>>>>> dwc3_alloc_scratch_buffers, dwc3_check_params and dwc3_debugfs_init.
>>>>>>>
>>>>>> Right. Thanks for narrowing it down. There are still many steps in
>>>>>> dwc3_core_init(). We have some suspicion, but we still haven't
>>>>>> confirmed
>>>>>> the exact cause of the failure. We can write a proper patch once we
>>>>>> know
>>>>>> the reason.
>>>>> If you would like me to test your suspicion, just tell me what to do
>>>>> :-)
>>>>
>>>> OK, Ferry, I think I'm going to need clarification on specifics on
>>>> your test setup. Can you share your kernel config, maybe your
>>>> "/proc/config.gz", somewhere? When you say you are running vanilla
>>>> Linux, do you mean it or do you mean vanilla tree + some patch delta?
>>>
>>> For v6.0 I can get the exacts tonight. But earlier I had this for v5.17:
>>>
>>> https://github.com/htot/meta-intel-edison/blob/master/meta-intel-edison-bsp/recipes-kernel/linux/linux-yocto_5.17.bb
>>>
>>>
>>> There are 2 patches referred in #67 and #68. One is related to the
>>> infinite loop. The other is I believe also needed to get dwc3 to work.
>>>
>>> All the kernel config are applied as .cfg.
>>>
>>> Patches and cfs's here:
>>>
>>> https://github.com/htot/meta-intel-edison/tree/master/meta-intel-edison-bsp/recipes-kernel/linux/files
>>>
>>
>> Updated Yocto recipe for v6.0 here:
>>
>> https://github.com/htot/meta-intel-edison/blob/honister/meta-intel-edison-bsp/recipes-kernel/linux/linux-yocto_6.0.bb
>>
>> #75-#77 are the 2 reverts from Andy, + one SOF revert (not related to
>> this thread).
> 
> Please drop all of this
> https://github.com/htot/meta-intel-edison/blob/honister/meta-intel-edison-bsp/recipes-kernel/linux/linux-yocto_6.0.bb#L69-L77
> and re do the testing. Assuming things are still broken, that's how
> you want to do the bisecting.

I removed 4 patches:
0043b-TODO-driver-core-Break-infinite-loop-when-deferred-p.patch
0044-REVERTME-usb-dwc3-gadget-skip-endpoints-ep-18-in-out.patch
0001-Revert-USB-fixup-for-merge-issue-with-usb-dwc3-Don-t.patch
0001-Revert-usb-dwc3-Don-t-switch-OTG-peripheral-if-extco.patch

and indeed as you expect kernel boots (no infinite loop). However dwc3 
host mode is not working as in your case, device mode works fine (Yocto 
configures a set of gadgets for me).

Just to be sure if I could have bisected without 0043a I added back the 
2 0001-Revert* and indeed I run into the infinite loop with the console 
spitting out continuous:
debugfs: Directory 'dwc3.0.auto' with parent 'ulpi' already present!
tusb1210 dwc3.0.auto.ulpi: error -110 writing val 0x41 to reg 0x80

so yes it seems either 0043b or your patch "usb: dwc3: Don't switch OTG 
-> peripheral if extcon is present" is needed to boot (break the 
infinite loop). But your patch is in my case not sufficient to make host 
mode work.

As I understand it depends a bit on the timing, I might have a different 
initrd (built by Yocto vs. Buildroot). F.i. I see I have 
extcon-intel-mrfld in initrd and dwc3 / phy-tusb1210 built-in.