Re: i2c designware change broke touchpad of a thinkpad

On Sun, 9 Aug 2026, Thorsten Leemhuis wrote:
> Sorry, picked the wrong file while preparing the mail, it's here:
> https://www.leemhuis.info/files/misc/dmesg_patch_dyndbg

Thanks, that's the one. Full timeline from that boot:

  0.619s  AMDI0010:00 and AMDI0010:01 defer (AMDI0030:00 not registered)
  1.136s  Retry succeeds: device_is_bound()=true for AMDI0030:00,
          confirmed for all three children (XXXX0000:00, SYNA8018:00,
          NXP1001:00)
  2.222s  lost arbitration on AMDI0010:01 (x3)
  3.260s  controller timed out, HID descriptor fetch fails

The dependency check itself is behaving correctly here -- it defers,
then correctly confirms AMDI0030:00 is bound before letting probe
continue. The arbitration failure happens over a second *after* that,
when the touchpad attempts its actual first transaction.

So this doesn't look like a logic bug in the check itself. My read: by
delaying dw_i2c_plat_probe() by ~500ms (correctly, for GPIO's sake),
something else ends up contending for the AMDI0010:01 bus by the time
the touchpad's first transaction actually happens -- a window that
the original (undeferred, earlier) probe attempt apparently avoided.

Mario -- does this look like a known AMD I2C/PSP semaphore contention
pattern to you? Wondering if there's a shared bus/firmware consumer
that could explain a ~1s-later collision like this, independent of
the GPIO controller itself being ready.

Thorsten, if you have it handy: /proc/interrupts and lsmod from this
boot would help narrow down what else might be touching that bus
around the 2.2s mark.

Thanks,
Hardik

On Mon, 10 Aug 2026 at 11:06, Thorsten Leemhuis <[email protected]> wrote:
>
> On 8/10/26 07:23, Hardik Prakash wrote:
> > On Sat, 8 Aug 2026, Thorsten Leemhuis wrote:
> >> https://www.leemhuis.info/files/misc/dmesg-master-plus_revert
> >>
> >> [    0.619018] i2c-dw-gpio-dbg: i2c_dw_check_gpio_dependencies(AMDI0010:00)
> >> [...]
> >> [    1.136010] i2c-dw-gpio-dbg: device_is_bound()=true for AMDI0030:00
> >
> > Thanks, this trace looks correct on its face (defer at 0.619s, retry
> > succeeds at 1.122-1.136s), but the link above points to the same file
> > you sent last round (the master+revert baseline, no debug patch, no
> > i2c-dw-gpio-dbg lines in it at all) rather than this new capture.
> >> Could you share the full, unfiltered dmesg from this exact boot (the
> > one with the debug patch applied)? I need to see where
> > "lost arbitration" falls relative to the trace above.
>
> Sorry, picked the wrong file while preparing the mail, it's here:
> https://www.leemhuis.info/files/misc/dmesg_patch_dyndbg
>
> Ciao, Thorsten
>
> > Separately, from your DSDT: NFC1 (NXP1001), which shows up as a child
> > of AMDI0010:01 in your trace, declares its _CRS as a raw resource
> > buffer containing three GPIO resources referencing \_SB.GPIO -- one
> > GpioIo and two separate GpioInt entries. Not sure yet if that's
> > relevant, but it's a pattern I haven't seen on my hardware
> > which I've tested against.
> >
> > Thanks,
> > Hardik
> >
> > On Sun, 9 Aug 2026 at 21:49, Thorsten Leemhuis <[email protected]> wrote:
> >>
> >> On 8/8/26 22:25, Andy Shevchenko wrote:
> >>> On Sat, Aug 08, 2026 at 10:31:28PM +0530, Hardik Prakash wrote:
> >>>> On Fri, 7 Aug 2026, Thorsten Leemhuis wrote:
> >>>>> This became 0a4bb2abc3e56d ("i2c: designware: defer probe if child
> >>>>> GpioInt controllers are not bound") and causes a regression for me: the
> >>>>> Touchpad in my ThinkPad T14s Gen 4 (AMD) stopped working. From the
> >>>>> kernel log:
> >>>>>
> >>>>> i2c_designware AMDI0010:01: i2c_dw_handle_tx_abort: lost arbitration
> >>>>> i2c_designware AMDI0010:01: controller timed out
> >>>>> i2c_hid_acpi i2c-SYNA8018:00: failed to fetch HID descriptor: -110
> >>>>> i2c_hid_acpi i2c-SYNA8018:00: Failed to fetch the HID Descriptor
> >>>>>
> >>>>> Reverting this change in current mainline/master (f9a2394a23482) fixed
> >>>>> things for me. Full dmesg of current master and master+revert can be
> >>>>> found here:
> >>>>>
> >>>>> https://www.leemhuis.info/files/misc/dmesg-master
> >>>>> https://www.leemhuis.info/files/misc/dmesg-master-plus_revert
> >>>> [...]
> >>>> Two things that would help narrow this down, whenever you have a moment:
> >>
> >> Thx for looking into this. Here we go:
> >>
> >>>> 1. A DSDT dump
> >>
> >> https://www.leemhuis.info/files/misc/dsdt.dsl
> >>
> >>>> 2. A dmesg with dynamic debug from a kernel built with the attached
> >>>>    patch on top of current mainline/master
> >>
> >> https://www.leemhuis.info/files/misc/dmesg-master-plus_revert
> >>
> >> [    0.619018] i2c-dw-gpio-dbg: i2c_dw_check_gpio_dependencies(AMDI0010:00)
> >> [    0.619018] i2c-dw-gpio-dbg: check_child_gpioint(adev=XXXX0000:00)
> >> [    0.619076] i2c-dw-gpio-dbg: GpioInt resource_source=\_SB.GPIO (len=10)
> >> [    0.619079] i2c-dw-gpio-dbg: acpi_fetch_acpi_dev() succeeded,
> >> device=AMDI0030:00
> >> [    0.619080] i2c-dw-gpio-dbg: gpio_device_find_by_fwnode() returned
> >> NULL, deferring
> >> [    0.619082] i2c-dw-gpio-dbg: check_child_gpioint ret=-517 (defer)
> >> [    0.619102] i2c-dw-gpio-dbg: i2c_dw_check_gpio_dependencies(AMDI0010:01)
> >> [    0.619104] i2c-dw-gpio-dbg: check_child_gpioint(adev=SYNA8018:00)
> >> [    0.619159] i2c-dw-gpio-dbg: GpioInt resource_source=\_SB.GPIO (len=10)
> >> [    0.619162] i2c-dw-gpio-dbg: acpi_fetch_acpi_dev() succeeded,
> >> device=AMDI0030:00
> >> [    0.619162] i2c-dw-gpio-dbg: gpio_device_find_by_fwnode() returned
> >> NULL, deferring
> >> [    0.619164] i2c-dw-gpio-dbg: check_child_gpioint ret=-517 (defer)
> >> [    1.122517] i2c-dw-gpio-dbg: i2c_dw_check_gpio_dependencies(AMDI0010:00)
> >> [    1.122523] i2c-dw-gpio-dbg: check_child_gpioint(adev=XXXX0000:00)
> >> [    1.122625] i2c-dw-gpio-dbg: GpioInt resource_source=\_SB.GPIO (len=10)
> >> [    1.122636] i2c-dw-gpio-dbg: acpi_fetch_acpi_dev() succeeded,
> >> device=AMDI0030:00
> >> [    1.122639] i2c-dw-gpio-dbg: gpio_device_find_by_fwnode() succeeded
> >> [    1.122642] i2c-dw-gpio-dbg: device_is_bound()=true for AMDI0030:00
> >> [    1.135894] i2c-dw-gpio-dbg: i2c_dw_check_gpio_dependencies(AMDI0010:01)
> >> [    1.135898] i2c-dw-gpio-dbg: check_child_gpioint(adev=SYNA8018:00)
> >> [    1.135976] i2c-dw-gpio-dbg: GpioInt resource_source=\_SB.GPIO (len=10)
> >> [    1.135980] i2c-dw-gpio-dbg: acpi_fetch_acpi_dev() succeeded,
> >> device=AMDI0030:00
> >> [    1.135983] i2c-dw-gpio-dbg: gpio_device_find_by_fwnode() succeeded
> >> [    1.135985] i2c-dw-gpio-dbg: device_is_bound()=true for AMDI0030:00
> >> [    1.135987] i2c-dw-gpio-dbg: check_child_gpioint(adev=NXP1001:00)
> >> [    1.136005] i2c-dw-gpio-dbg: GpioInt resource_source=\_SB.GPIO (len=10)
> >> [    1.136008] i2c-dw-gpio-dbg: acpi_fetch_acpi_dev() succeeded,
> >> device=AMDI0030:00
> >> [    1.136009] i2c-dw-gpio-dbg: gpio_device_find_by_fwnode() succeeded
> >> [    1.136010] i2c-dw-gpio-dbg: device_is_bound()=true for AMDI0030:00
> >>
> >> HTH, Ciao, Thorsten
> >>
> >>>> On Fri, 7 Aug 2026 at 19:37, Thorsten Leemhuis <[email protected]> wrote:
> >>>>> On 7/28/26 10:30, Andi Shyti wrote:
> >>>>>> On Sat, Jul 18, 2026 at 11:13:31AM +0530, Hardik Prakash wrote:
> >>>>>>> I2C controllers may have child devices with GpioInt resources that
> >>>>>>> depend on GPIO controllers being fully initialized. If the I2C
> >>>>>>> controller probes and enumerates children before the referenced GPIO
> >>>>>>> controller has completed probe, GPIO interrupts may not be properly
> >>>>>>> configured, leading to device failures.
> >>>>>>>
> >>>>>>> On Lenovo Yoga 7 14AGP11, the WACF2200 touchscreen (child of
> >>>>>>> AMDI0010:02) has a GpioInt resource pointing to GPIO 157 on the
> >>>>>>> pinctrl-amd controller (AMDI0030:00). When i2c-designware probes
> >>>>>>> AMDI0010:02 before pinctrl-amd finishes initializing, I2C transactions
> >>>>>>> fail with lost arbitration errors:
> >>>>>>>
> >>>>>>>   0.285952  amd_gpio_probe: registering gpiochip  <- GPIO chip visible
> >>>>>>>   0.287121  amd_gpio_probe: requesting parent IRQ <- probe still running
> >>>>>>>   0.301454  AMDI0010:02 dw_i2c_plat_probe: start  <- races here
> >>>>>>>   2.348157  lost arbitration
> >>>>>>>
> >>>>>>> Add a dependency check that walks ACPI child devices and defers probe
> >>>>>>> until any referenced GPIO controller is bound.
> >>>
> >>> [...]
> >>>
> >>>>> #regzbot introduced: 0a4bb2abc3e56d
> >>>>> #regzbot title i2c: designware: ThinkPad touchpad broke
> >>>
> >>
> >
>