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

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Date:   Mon, 10 Oct 2022 14:35:53 -0700
From:   Andrey Smirnov <andrew.smirnov@...il.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>,
        "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 Mon, Oct 10, 2022 at 1:52 PM Ferry Toth <fntoth@...il.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@...il.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.