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

Ferry Toth
2022-10-10T20:52:47Z

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).

Otherwise via the git route, https://github.com/andy-shev/linux should
lead to the same, although you might want to drop "WIP: serial:
8250_dma: use sgl on transmit "

>
>> The reason I'm asking is because I'm having a hard time reproducing
>> the problem on my end. In fact, when I build v6.0
>> (4fe89d07dcc2804c8b562f6c7896a45643d34b2f) and then do a
>>
>> git revert 8bd6b8c4b100 0f0101719138 (original revert proposed by Andy)
>>
>> I get an infinite loop of reprobing that looks something like (some
>> debug tracing, function name + line number, included):
>>
>> [    6.160732] tusb1210 dwc3.0.auto.ulpi: error -110 writing val 0x41
>> to reg 0x80
>> [    6.172299] XXXXXXXXXXX: dwc3_probe 1834
>> [    6.172426] XXXXXXXXXXX: dwc3_core_init_mode 1386
>> [    6.176391] XXXXXXXXXXX: dwc3_drd_init 593
>> [    6.181573] dwc3 dwc3.0.auto: Driver dwc3 requests probe deferral
>> [    6.191886] platform dwc3.0.auto: Added to deferred list
>> [    6.197249] platform dwc3.0.auto: Retrying from deferred list
>> [    6.203057] bus: 'platform': __driver_probe_device: matched device
>> dwc3.0.auto with driver dwc3
>> [    6.211783] bus: 'platform': really_probe: probing driver dwc3 with
>> device dwc3.0.auto
>> [    6.219935] XXXXXXXXXXX: dwc3_probe 1822
>> [    6.219952] XXXXXXXXXXX: dwc3_core_init 1092
>> [    6.223903] XXXXXXXXXXX: dwc3_core_init 1095
>> [    6.234839] bus: 'ulpi': __driver_probe_device: matched device
>> dwc3.0.auto.ulpi with driver tusb1210
>> [    6.248335] bus: 'ulpi': really_probe: probing driver tusb1210 with
>> device dwc3.0.auto.ulpi
>> [    6.257039] driver: 'tusb1210': driver_bound: bound to device
>> 'dwc3.0.auto.ulpi'
>> [    6.264501] bus: 'ulpi': really_probe: bound device
>> dwc3.0.auto.ulpi to driver tusb1210
>> [    6.272553] debugfs: Directory 'dwc3.0.auto' with parent 'ulpi'
>> already present!
>> [    6.279978] XXXXXXXXXXX: dwc3_core_init 1099
>> [    6.279991] XXXXXXXXXXX: dwc3_core_init 1103
>> [    6.345769] tusb1210 dwc3.0.auto.ulpi: error -110 writing val 0x41
>> to reg 0x80
>> [    6.357316] XXXXXXXXXXX: dwc3_probe 1834
>> [    6.357447] XXXXXXXXXXX: dwc3_core_init_mode 1386
>> [    6.361402] XXXXXXXXXXX: dwc3_drd_init 593
>> [    6.366589] dwc3 dwc3.0.auto: Driver dwc3 requests probe deferral
>> [    6.376901] platform dwc3.0.auto: Added to deferred list
>>
>> which renders the system completely unusable, but USB host is
>> definitely going to be broken too. Now, ironically, with my patch
>> in-place, an attempt to probe extcon that ends up deferring the probe
>> happens before the ULPI driver failure (which wasn't failing driver
>> probe prior to
>> https://lore.kernel.org/all/20220213130524.18748-7-hdegoede@redhat.com/),
>> there no "driver binding" event that re-triggers deferred probe
>> causing the loop, so the system progresses to a point where extcon is
>> available and dwc3 driver eventually loads.
>>
>> After that, and I don't know if I'm doing the same test, USB host
>> seems to work as expected. lsusb works, my USB stick enumerates as
>> expected. Switching the USB mux to micro-USB and back shuts the host
>> functionality down and brings it up as expected. Now I didn't try to
>> load any gadgets to make sure USB gadget works 100%, but since you
>> were saying it was USB host that was broken, I wasn't concerned with
>> that. Am I doing the right test?
>>
>> For the reference what I test with is:
>>   - vanilla kernel, no patch delta (sans minor debug tracing) + initrd
>> built with Buildroot 2022.08.1
>>   - Initrd is using systemd (don't think that really matters, but who
>> knows)
>>   - U-Boot 2022.04 (built with Buildroot as well)
>>   - kernel config is x86_64_defconfig + whatever I gathered from *.cfg
>> files in
>> https://github.com/edison-fw/meta-intel-edison/tree/master/meta-intel-edison-bsp/recipes-kernel/linux/files