Re: [PATCH v13] i2c: designware: defer probe if child GpioInt controllers are not bound

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.

Reviewed-by: Andy Shevchenko <[email protected]>

One nit-pick below. No need to resend, hopefully Andi can tweak that
whilst applying.

...

> +static int check_gpioint_resource(struct acpi_resource *ares, void *data)
> +{
> +	struct acpi_resource_gpio *agpio;
> +	struct acpi_device *gpio_adev;
> +	struct device *gpio_dev;
> +	acpi_handle handle;
> +	acpi_status status;
> +
> +	if (!acpi_gpio_get_irq_resource(ares, &agpio))
> +		return 1; /* not a GpioInt resource, skip */
> +
> +	if (!agpio->resource_source.string_length)
> +		return 1; /* no named controller, skip */
> +
> +	status = acpi_get_handle(NULL, agpio->resource_source.string_ptr, &handle);
> +	if (ACPI_FAILURE(status))
> +		return 1;
> +
> +	gpio_adev = acpi_fetch_acpi_dev(handle);
> +	if (!gpio_adev)
> +		return 1;
> +
> +	struct gpio_device *gdev __free(gpio_device_put) =
> +		gpio_device_find_by_fwnode(acpi_fwnode_handle(gpio_adev));
> +	if (!gdev)
> +		return -EPROBE_DEFER; /* controller not registered yet: abort walk */
> +
> +	gpio_dev = gpio_device_to_device(gdev)->parent;
> +
> +	guard(device)(gpio_dev);

+ blank line here as well. I asked to add blank lines before and after.

  "...make sure it has a blank lines before and after, so it's visible
   as a separate entity."

> +	if (!device_is_bound(gpio_dev))
> +		return -EPROBE_DEFER; /* controller not bound yet: abort walk */
> +
> +	return 1; /* bound, skip adding to resource list, continue walk */
> +}

-- 
With Best Regards,
Andy Shevchenko