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 03:38:37PM +0530, 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

In case this goes in via some other tree:

Acked-by: Wolfram Sang <wsa+renesas@sang-engineering.com>


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