Re: [PATCH v6 1/1] i2c: designware: defer probe if child GpioInt controllers are not bound

[Mario Limonciello <superm1@kernel.org>]

On 5/26/26 11:42, Bartosz Golaszewski wrote:
> On Sat, 23 May 2026 19:44:40 +0200, Hardik Prakash
> <hardikprakash.official@gmail.com> said:
>> 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>
>> Assisted-by: Claude:claude-sonnet-4-6
>> Assisted-by: GPT-Codex:gpt-5.2-codex
>> BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=221494
> 
> I don't think we use this tag anymore. Just make it Link:
> 
> Acked-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>

Please make sure that we drop the now unnecessary patch that was 
committed from the earlier series when queuing this.  If that has 
already made it into a PR to linus (as part of -fixes or so) we should 
get it reverted.