Message-ID: <CAHQ1cqGSXoUTopwvrQtLww5M0Tf=6F505ziLn+wGHhW_8-JhFQ@mail.gmail.com>
Date:   Tue, 11 Oct 2022 13:50:26 -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 Tue, Oct 11, 2022 at 11:54 AM Ferry Toth <fntoth@...il.com> wrote:
>
> Hi,
>
> Op 10-10-2022 om 23:35 schreef Andrey Smirnov:
> > 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.
>
> 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

Please remove all custom patches so we are on the same page. I don't
suspect the 8250 related changes to affect anything, but I also would
like to be testing the same thing. I'm testing vanilla v6.0

>
> 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).

What do you do to test host mode working? lsusb? Something else?
Asking to make sure I'm doing something equivalent on my end.

>
> 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.
>

Next step would be to establish if USB is working before my patch. You
should be able to avoid the boot loop if you disable the
"phy-tusb1210" driver. The driver fails to probe anyway, so it's not
very likely to be crucial for functioning, so it should allow you to
try things with my patch reverted:

git revert 8bd6b8c4b100 0f0101719138

After that, if things start working, it'd make sense to re-do your
function re-arranging experiment to re-validate it.

> 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.
>

You mentioned that your rootfs image does some gadget configuration
for you. Can this be disabled? If yes, it'd make sense to check if
this could be a variable explaining the difference.

What U-Boot version are you running? AFACT U-Boot will touch that
particular IP block, so this might be somewhat relevant.

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