Date:   Wed, 15 Mar 2023 17:39:47 +0100
From:   Fabrice Gasnier <fabrice.gasnier@...s.st.com>
To:     Saravana Kannan <saravanak@...gle.com>
CC:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Guenter Roeck <linux@...ck-us.net>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Daniel Scally <djrscally@...il.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Len Brown <lenb@...nel.org>,
        Yongqin Liu <yongqin.liu@...aro.org>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Martin Kepplinger <martin.kepplinger@...i.sm>,
        Amelie Delaunay <amelie.delaunay@...s.st.com>,
        <kernel-team@...roid.com>, <linux-kernel@...r.kernel.org>,
        <linux-usb@...r.kernel.org>, <linux-acpi@...r.kernel.org>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        <linux-stm32@...md-mailman.stormreply.com>
Subject: Re: [PATCH v1 0/4] Remove use of fw_devlink_purge_absent_suppliers()

On 3/10/23 18:40, Saravana Kannan wrote:
> On Fri, Mar 10, 2023 at 9:21 AM Fabrice Gasnier
> <fabrice.gasnier@...s.st.com> wrote:
>>
>> On 3/1/23 22:49, Saravana Kannan wrote:
>>> Yongqin, Martin, Amelie,
>>>
>>> We recent refactor of fw_devlink that ends with commit fb42378dcc7f
>>> ("mtd: mtdpart: Don't create platform device that'll never probe"),
>>> fw_devlink is smarter and doesn't depend on compatible property. So, I
>>> don't think these calls are needed anymore. But I don't have these
>>> devices to test on and be sure and the hardware I use to test changes
>>> doesn't have this issue either.
>>>
>>> Can you please test these changes on the hardware where you hit the
>>> issue to make sure things work as expected?
>>
>>
>> Hi Saravana,
>>
>> Sorry for the late reply,
> 
> Thanks for testing!
> 
>> On behalf of Amelie, I did some testing on STM32MP15 DK2 board, on top
>> of commit fb42378dcc7f, and also with your series applied.
>> For reference, it's based on: arch/arm/boot/dts/stm32mp15xx-dkx.dtsi
>>
>> I noticed some error messages on this board, since the 12 patch series,
>> around the I2C PMIC device links:
>>
>> [    3.585514] i2c 1-0033: Failed to create device link with 1-0033
>> [    3.590115] i2c 1-0033: Failed to create device link with 1-0033
>> [    3.596278] i2c 1-0033: Failed to create device link with 1-0033
>> [    3.602188] i2c 1-0033: Failed to create device link with 1-0033
>> [    3.608165] i2c 1-0033: Failed to create device link with 1-0033
>> [    3.614278] i2c 1-0033: Failed to create device link with 1-0033
>> [    3.620256] i2c 1-0033: Failed to create device link with 1-0033
>> [    3.626253] i2c 1-0033: Failed to create device link with 1-0033
>> [    3.632252] i2c 1-0033: Failed to create device link with 1-0033
>> [    3.639001] stpmic1 1-0033: PMIC Chip Version: 0x10
>> [    3.645398] platform 5c002000.i2c:stpmic@33:regulators: Fixed
>> dependency cycle(s) with /soc/i2c@...0200
>> 0/stpmic@...regulators/boost
>> [    3.655937] platform 5c002000.i2c:stpmic@33:regulators: Fixed
>> dependency cycle(s) with /soc/i2c@...0200
>> 0/stpmic@...regulators/buck2
>> [    3.667824] platform 5c002000.i2c:stpmic@33:regulators: Fixed
>> dependency cycle(s) with /soc/i2c@...0200
>> 0/stpmic@...regulators/buck4
>> [    3.719751] stpmic1-regulator 5c002000.i2c:stpmic@33:regulators:
>> Failed to create device link with 1-0033
>> [    3.728099] stpmic1-regulator 5c002000.i2c:stpmic@33:regulators:
>> Failed to create device link with 1-0033
>> [    3.737576] stpmic1-regulator 5c002000.i2c:stpmic@33:regulators:
>> Failed to create device link with 1-0033
>> [    3.747216] stpmic1-regulator 5c002000.i2c:stpmic@33:regulators:
>> Failed to create device link with 1-0033
>> [    3.756750] stpmic1-regulator 5c002000.i2c:stpmic@33:regulators:
>> Failed to create device link with 1-0033
>> [    3.766382] stpmic1-regulator 5c002000.i2c:stpmic@33:regulators:
>> Failed to create device link with 1-0033
>> [    3.775914] stpmic1-regulator 5c002000.i2c:stpmic@33:regulators:
>> Failed to create device link with 1-0033
>> [    3.785545] stpmic1-regulator 5c002000.i2c:stpmic@33:regulators:
>> Failed to create device link with 1-0033
> 
> You can ignore all the "Failed to create device link" errors. They are
> just error logs for stuff that was being ignored silently before. So
> that's no functional regression AFAIK. I'll fix them separately if
> necessary. And I'm sure you'll see these messages even without my
> fw_devlink refactor series.

Hi Saravana,

Thanks for the information.

I tested without the 12 patch series, just before commit 3a2dbc510c43
"driver core: fw_devlink: Don't purge child fwnode's consumer links".

I don't see the messages here. But I can see these on top of fb42378dcc7f.


> 
>> Strangely some of the regulators seems to have "Fixed dependency", but
>> not all.
> 
> Yeah, that's fine too -- that's just fw_devlink being verbose about
> not enforcing probe ordering between devices in that cycle because it
> can't tell which one of the dependencies is not a probe requirement.
> Maybe I'll make it a dbg log if it's confusing people.
> 
>> Regarding the typec stusb160x I noticed the message below. It seems
>> correct, right ?
>>
>> [   15.962771] typec port0: Fixed dependency cycle(s) with
>> /soc/usb-otg@...00000/port/endpoint
> 
> I don't know if there is a cyclic dependency in your DT or not. But
> this message itself is not an issue.

Ack,

> 
>> But sometimes (lets say 1/5 times) during boot, when I have a cable
>> already plugged in, it looks like there's some race condition. The dwc2
>> driver reports some error logs in a loop, indefinitely, up to the
>> watchdog resets the platform :-(.
> 
> Can you try this series (the one you are testing) without my
> fw_devlink refactor that ends with commit fb42378dcc7f? Trying to make
> sure we can reproduce the issue Amelie was fixing before I claim my
> refactor series fixes it.

Strangely, I tested without the series, and removed earlier patch from
Amelie. I don't reproduce the issue she used to hit.

> 
>> [   16.288458] dwc2 49000000.usb-otg: Mode Mismatch Interrupt: currently
>> in Host mode
>> [   16.288490] dwc2 49000000.usb-otg: Mode Mismatch Interrupt: currently
>> in Host mode
>> [   16.310429] dwc2 49000000.usb-otg: Mode Mismatch Interrupt: currently
>> in Host mode
>>
>> It probably just points some already existing race condition here. Maybe
>> it isn't even linked to this patch. But I have no evidence at this
>> stage. I hope I can investigate further on this one, hopefully I can
>> free up some time for that.
> 
> If you never pick up this series, are you not having any of these 1/5
> times boot issues? I wouldn't expect my changes to add any races, but
> I'll wait to see what you find here.

Some good news here is, I've identified a recent change [1], that
creates the issue pointed above. I just sent a separate patch [2] for this.
So, it's not related to this series. (I managed to reproduce without
picking it).

[1]
https://lore.kernel.org/r/20221206-dwc2-gadget-dual-role-v1-2-36515e1092cd@theobroma-systems.com
[2]
https://lore.kernel.org/lkml/20230315144433.3095859-1-fabrice.gasnier@foss.st.com/

So for stusb160x: e.g. PATCH 1, feel free to add on my:
Tested-by: Fabrice Gasnier <fabrice.gasnier@...s.st.com>

Best Regards,
Fabrice

> 
> Thanks,
> Saravana
> 
>>
>> Best Regards,
>> Fabrice
>>
>>>
>>> Yongqin, If you didn't have the context, this affected hikey960.
>>>
>>> Greg,
>>>
>>> Let's wait for some tests before we land these.
>>>
>>> Thanks,
>>> Saravana
>>>
>>> Cc: Yongqin Liu <yongqin.liu@...aro.org>
>>> Cc: Sumit Semwal <sumit.semwal@...aro.org>
>>> Cc: Martin Kepplinger <martin.kepplinger@...i.sm>
>>> Cc: Amelie Delaunay <amelie.delaunay@...s.st.com>
>>>
>>> Saravana Kannan (4):
>>>   usb: typec: stusb160x: Remove use of
>>>     fw_devlink_purge_absent_suppliers()
>>>   usb: typec: tipd: Remove use of fw_devlink_purge_absent_suppliers()
>>>   usb: typec: tcpm: Remove use of fw_devlink_purge_absent_suppliers()
>>>   driver core: Delete fw_devlink_purge_absent_suppliers()
>>>
>>>  drivers/base/core.c           | 16 ----------------
>>>  drivers/usb/typec/stusb160x.c |  9 ---------
>>>  drivers/usb/typec/tcpm/tcpm.c |  9 ---------
>>>  drivers/usb/typec/tipd/core.c |  9 ---------
>>>  include/linux/fwnode.h        |  1 -
>>>  5 files changed, 44 deletions(-)
>>>
>>
>> --
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>>

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