Re: [PATCH v8 2/2] i2c: designware: defer probe if child GpioInt controllers are not bound

[Wolfram Sang <wsa+renesas@sang-engineering.com>]

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On Fri, May 29, 2026 at 12:12:31PM +0200, Mario Limonciello wrote:
> 
> 
> On 5/29/26 12:08, Hardik Prakash wrote:
> > I2C controllers may have child devices with GpioInt resources that
> > depend on GPIO controllers to be 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
> > occur before the GPIO IRQ quirk in amd_gpio_probe() has run, causing:
> > 
> >    i2c_designware AMDI0010:02: i2c_dw_handle_tx_abort: lost arbitration
> > 
> > Add a generic dependency check in i2c-designware that walks ACPI child
> > devices, identifies any GpioInt resources, resolves the referenced GPIO
> > controllers, and defers probe if those controllers are not yet bound.
> > 
> > This ensures GPIO controllers complete initialization (including IRQ
> > setup and quirks) before I2C child enumeration begins, fixing the race
> > without device-specific quirks or DMI matching.
> > 
> > The probe ordering race was confirmed via dynamic debug tracing:
> > 
> >    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
> > 
> > Suggested-by: Mario Limonciello <mario.limonciello@amd.com>
> > Signed-off-by: Hardik Prakash <hardikprakash.official@gmail.com>
> > Acked-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
> > Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
> > Assisted-by: Claude:claude-sonnet-4-6
> > Assisted-by: GPT-Codex:gpt-5.2-codex
> > Reported-by: kernel test robot <lkp@intel.com>
> > Closes: https://lore.kernel.org/oe-kbuild-all/202605240959.Kcf1lIg4-lkp@intel.com/
> > Link: https://bugzilla.kernel.org/show_bug.cgi?id=221494
> 
> Fixes: 3812a9e84265a ("pinctrl-amd: enable IRQ for WACF2200 touchscreen on
> Lenovo Yoga 7 14AGP11")

No Rev-by from you, Mario?


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