[PATCH] Revert "i2c: designware: defer probe if child GpioInt controllers are not bound"

[PATCH] Revert "i2c: designware: defer probe if child GpioInt controllers are not bound"

[Hardik Prakash]

This reverts commit 0a4bb2abc3e56d7be6e69b050c88ba52c87e22bf.

The reverted commit causes a regression on ThinkPad T14s Gen 4 (AMD):
the touchpad's I2C controller fails with lost arbitration errors,
because it delays i2c-designware's probe by roughly 500ms, which
shifts the touchpad's first HID descriptor fetch into a window where
the platform's embedded controller is still acting as a secondary I2C
bus master. Debug tracing confirms the GpioInt dependency check itself
behaves correctly (it defers appropriately and confirms the GPIO
controller is bound); the arbitration failure happens roughly a
second after the check passes, when i2c_hid_acpi's own probe attempts
its first transaction.

The original fix is still needed for the Lenovo Yoga 7 14AGP11
touchscreen race the commit addressed, but a corrected version will
be resubmitted once the EC bus-mastering interaction is understood
and handled properly, rather than reintroducing a different
regression on more widely-used ThinkPad hardware in the meantime.

Reported-by: Thorsten Leemhuis <linux@leemhuis.info>
Closes: https://lore.kernel.org/all/b4a4eadb-282f-464c-843a-19d415a34d0c@leemhuis.info/
Signed-off-by: Hardik Prakash <hardikprakash.official@gmail.com>
---
 drivers/i2c/busses/i2c-designware-platdrv.c | 80 ---------------------
 1 file changed, 80 deletions(-)

diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index c8a203fff4d1..6d6e81242f74 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -8,14 +8,12 @@
  * Copyright (C) 2007 MontaVista Software Inc.
  * Copyright (C) 2009 Provigent Ltd.
  */
-#include <linux/acpi.h>
 #include <linux/clk-provider.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/dmi.h>
 #include <linux/err.h>
 #include <linux/errno.h>
-#include <linux/gpio/driver.h>
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
@@ -132,80 +130,6 @@ static int i2c_dw_probe_lock_support(struct dw_i2c_dev *dev)
 	return 0;
 }
 
-#if defined(CONFIG_ACPI) && defined(CONFIG_GPIOLIB)
-/*
- * Check whether an ACPI GpioInt resource's referenced GPIO controller
- * has finished probing. Resources with no named controller (resource
- * source string) are skipped, since they can't be resolved to a
- * struct device.
- */
-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);
-	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 */
-}
-
-static int check_child_gpioint(struct acpi_device *adev, void *data)
-{
-	LIST_HEAD(res_list);
-	int ret;
-
-	ret = acpi_dev_get_resources(adev, &res_list, check_gpioint_resource, NULL);
-	if (ret < 0)
-		return ret;
-
-	acpi_dev_free_resource_list(&res_list);
-
-	return 0;
-}
-
-static int i2c_dw_check_gpio_dependencies(struct device *dev)
-{
-	struct acpi_device *adev;
-
-	adev = ACPI_COMPANION(dev);
-	if (!adev)
-		return 0;
-
-	return acpi_dev_for_each_child(adev, check_child_gpioint, NULL);
-}
-#else
-static int i2c_dw_check_gpio_dependencies(struct device *dev)
-{
-	return 0;
-}
-#endif /* CONFIG_ACPI && CONFIG_GPIOLIB */
-
 static int dw_i2c_plat_probe(struct platform_device *pdev)
 {
 	u32 flags = (uintptr_t)device_get_match_data(&pdev->dev);
@@ -214,10 +138,6 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
 	struct dw_i2c_dev *dev;
 	int irq, ret;
 
-	ret = i2c_dw_check_gpio_dependencies(device);
-	if (ret)
-		return ret;
-
 	irq = platform_get_irq_optional(pdev, 0);
 	if (irq == -ENXIO)
 		flags |= ACCESS_POLLING;

base-commit: 3d6d817622b0a9721e3cc404df3469171582be13
-- 
2.55.0

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

[Thorsten Leemhuis]

On 8/14/26 12:07, Hardik Prakash wrote:
> This reverts commit 0a4bb2abc3e56d7be6e69b050c88ba52c87e22bf.

@Andi Shyti, would be great if you could pick this up and send it to
Linus for 7.2 (aka soon) or ask him to apply this from here. But from a
quick search on lore it looks like you are busy, on vacation, or
something. No worries, but therefore I might ask Linus to pull this
directly tomorrow to ensure this makes it into 7.2, as mentioned
yesterday already here:
https://lore.kernel.org/all/9095d7c8-92fe-4163-98f8-a53bbcefd6cb@leemhuis.info/

> The reverted commit causes a regression on ThinkPad T14s Gen 4 (AMD):
> the touchpad's I2C controller fails with lost arbitration errors,
> because it delays i2c-designware's probe by roughly 500ms, which
> shifts the touchpad's first HID descriptor fetch into a window where
> the platform's embedded controller is still acting as a secondary I2C
> bus master. Debug tracing confirms the GpioInt dependency check itself
> behaves correctly (it defers appropriately and confirms the GPIO
> controller is bound); the arbitration failure happens roughly a
> second after the check passes, when i2c_hid_acpi's own probe attempts
> its first transaction.
> 
> The original fix is still needed for the Lenovo Yoga 7 14AGP11
> touchscreen race the commit addressed, but a corrected version will
> be resubmitted once the EC bus-mastering interaction is understood
> and handled properly, rather than reintroducing a different
> regression on more widely-used ThinkPad hardware in the meantime.
> 
> Reported-by: Thorsten Leemhuis <linux@leemhuis.info>

Tested-by: Thorsten Leemhuis <linux@leemhuis.info>

Ciao, Thorsten

> Closes: https://lore.kernel.org/all/b4a4eadb-282f-464c-843a-19d415a34d0c@leemhuis.info/
> Signed-off-by: Hardik Prakash <hardikprakash.official@gmail.com>
> ---
>  drivers/i2c/busses/i2c-designware-platdrv.c | 80 ---------------------
>  1 file changed, 80 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
> index c8a203fff4d1..6d6e81242f74 100644
> --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> @@ -8,14 +8,12 @@
>   * Copyright (C) 2007 MontaVista Software Inc.
>   * Copyright (C) 2009 Provigent Ltd.
>   */
> -#include <linux/acpi.h>
>  #include <linux/clk-provider.h>
>  #include <linux/clk.h>
>  #include <linux/delay.h>
>  #include <linux/dmi.h>
>  #include <linux/err.h>
>  #include <linux/errno.h>
> -#include <linux/gpio/driver.h>
>  #include <linux/i2c.h>
>  #include <linux/interrupt.h>
>  #include <linux/io.h>
> @@ -132,80 +130,6 @@ static int i2c_dw_probe_lock_support(struct dw_i2c_dev *dev)
>  	return 0;
>  }
>  
> -#if defined(CONFIG_ACPI) && defined(CONFIG_GPIOLIB)
> -/*
> - * Check whether an ACPI GpioInt resource's referenced GPIO controller
> - * has finished probing. Resources with no named controller (resource
> - * source string) are skipped, since they can't be resolved to a
> - * struct device.
> - */
> -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);
> -	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 */
> -}
> -
> -static int check_child_gpioint(struct acpi_device *adev, void *data)
> -{
> -	LIST_HEAD(res_list);
> -	int ret;
> -
> -	ret = acpi_dev_get_resources(adev, &res_list, check_gpioint_resource, NULL);
> -	if (ret < 0)
> -		return ret;
> -
> -	acpi_dev_free_resource_list(&res_list);
> -
> -	return 0;
> -}
> -
> -static int i2c_dw_check_gpio_dependencies(struct device *dev)
> -{
> -	struct acpi_device *adev;
> -
> -	adev = ACPI_COMPANION(dev);
> -	if (!adev)
> -		return 0;
> -
> -	return acpi_dev_for_each_child(adev, check_child_gpioint, NULL);
> -}
> -#else
> -static int i2c_dw_check_gpio_dependencies(struct device *dev)
> -{
> -	return 0;
> -}
> -#endif /* CONFIG_ACPI && CONFIG_GPIOLIB */
> -
>  static int dw_i2c_plat_probe(struct platform_device *pdev)
>  {
>  	u32 flags = (uintptr_t)device_get_match_data(&pdev->dev);
> @@ -214,10 +138,6 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
>  	struct dw_i2c_dev *dev;
>  	int irq, ret;
>  
> -	ret = i2c_dw_check_gpio_dependencies(device);
> -	if (ret)
> -		return ret;
> -
>  	irq = platform_get_irq_optional(pdev, 0);
>  	if (irq == -ENXIO)
>  		flags |= ACCESS_POLLING;
> 
> base-commit: 3d6d817622b0a9721e3cc404df3469171582be13

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

[Mario Limonciello]

On 8/14/26 05:07, Hardik Prakash wrote:
> This reverts commit 0a4bb2abc3e56d7be6e69b050c88ba52c87e22bf.
> 
> The reverted commit causes a regression on ThinkPad T14s Gen 4 (AMD):
> the touchpad's I2C controller fails with lost arbitration errors,
> because it delays i2c-designware's probe by roughly 500ms, which
> shifts the touchpad's first HID descriptor fetch into a window where
> the platform's embedded controller is still acting as a secondary I2C
> bus master. Debug tracing confirms the GpioInt dependency check itself
> behaves correctly (it defers appropriately and confirms the GPIO
> controller is bound); the arbitration failure happens roughly a
> second after the check passes, when i2c_hid_acpi's own probe attempts
> its first transaction.
> 
> The original fix is still needed for the Lenovo Yoga 7 14AGP11
> touchscreen race the commit addressed, but a corrected version will
> be resubmitted once the EC bus-mastering interaction is understood
> and handled properly, rather than reintroducing a different
> regression on more widely-used ThinkPad hardware in the meantime.
> 
> Reported-by: Thorsten Leemhuis <linux@leemhuis.info>
> Closes: https://lore.kernel.org/all/b4a4eadb-282f-464c-843a-19d415a34d0c@leemhuis.info/
> Signed-off-by: Hardik Prakash <hardikprakash.official@gmail.com>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>> ---
>   drivers/i2c/busses/i2c-designware-platdrv.c | 80 ---------------------
>   1 file changed, 80 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
> index c8a203fff4d1..6d6e81242f74 100644
> --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> @@ -8,14 +8,12 @@
>    * Copyright (C) 2007 MontaVista Software Inc.
>    * Copyright (C) 2009 Provigent Ltd.
>    */
> -#include <linux/acpi.h>
>   #include <linux/clk-provider.h>
>   #include <linux/clk.h>
>   #include <linux/delay.h>
>   #include <linux/dmi.h>
>   #include <linux/err.h>
>   #include <linux/errno.h>
> -#include <linux/gpio/driver.h>
>   #include <linux/i2c.h>
>   #include <linux/interrupt.h>
>   #include <linux/io.h>
> @@ -132,80 +130,6 @@ static int i2c_dw_probe_lock_support(struct dw_i2c_dev *dev)
>   	return 0;
>   }
>   
> -#if defined(CONFIG_ACPI) && defined(CONFIG_GPIOLIB)
> -/*
> - * Check whether an ACPI GpioInt resource's referenced GPIO controller
> - * has finished probing. Resources with no named controller (resource
> - * source string) are skipped, since they can't be resolved to a
> - * struct device.
> - */
> -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);
> -	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 */
> -}
> -
> -static int check_child_gpioint(struct acpi_device *adev, void *data)
> -{
> -	LIST_HEAD(res_list);
> -	int ret;
> -
> -	ret = acpi_dev_get_resources(adev, &res_list, check_gpioint_resource, NULL);
> -	if (ret < 0)
> -		return ret;
> -
> -	acpi_dev_free_resource_list(&res_list);
> -
> -	return 0;
> -}
> -
> -static int i2c_dw_check_gpio_dependencies(struct device *dev)
> -{
> -	struct acpi_device *adev;
> -
> -	adev = ACPI_COMPANION(dev);
> -	if (!adev)
> -		return 0;
> -
> -	return acpi_dev_for_each_child(adev, check_child_gpioint, NULL);
> -}
> -#else
> -static int i2c_dw_check_gpio_dependencies(struct device *dev)
> -{
> -	return 0;
> -}
> -#endif /* CONFIG_ACPI && CONFIG_GPIOLIB */
> -
>   static int dw_i2c_plat_probe(struct platform_device *pdev)
>   {
>   	u32 flags = (uintptr_t)device_get_match_data(&pdev->dev);
> @@ -214,10 +138,6 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
>   	struct dw_i2c_dev *dev;
>   	int irq, ret;
>   
> -	ret = i2c_dw_check_gpio_dependencies(device);
> -	if (ret)
> -		return ret;
> -
>   	irq = platform_get_irq_optional(pdev, 0);
>   	if (irq == -ENXIO)
>   		flags |= ACCESS_POLLING;
> 
> base-commit: 3d6d817622b0a9721e3cc404df3469171582be13

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

[Andi Shyti]

Hi Hardik,

On Fri, Aug 14, 2026 at 03:37:19PM +0530, Hardik Prakash wrote:
> This reverts commit 0a4bb2abc3e56d7be6e69b050c88ba52c87e22bf.
> 
> The reverted commit causes a regression on ThinkPad T14s Gen 4 (AMD):
> the touchpad's I2C controller fails with lost arbitration errors,
> because it delays i2c-designware's probe by roughly 500ms, which
> shifts the touchpad's first HID descriptor fetch into a window where
> the platform's embedded controller is still acting as a secondary I2C
> bus master. Debug tracing confirms the GpioInt dependency check itself
> behaves correctly (it defers appropriately and confirms the GPIO
> controller is bound); the arbitration failure happens roughly a
> second after the check passes, when i2c_hid_acpi's own probe attempts
> its first transaction.
> 
> The original fix is still needed for the Lenovo Yoga 7 14AGP11
> touchscreen race the commit addressed, but a corrected version will
> be resubmitted once the EC bus-mastering interaction is understood
> and handled properly, rather than reintroducing a different
> regression on more widely-used ThinkPad hardware in the meantime.
> 
> Reported-by: Thorsten Leemhuis <linux@leemhuis.info>
> Closes: https://lore.kernel.org/all/b4a4eadb-282f-464c-843a-19d415a34d0c@leemhuis.info/
> Signed-off-by: Hardik Prakash <hardikprakash.official@gmail.com>

merged to i2c/i2c-2.

Thanks,
Andi

[PATCH] Revert "i2c: designware: defer probe if child GpioInt controllers are not bound"

[Hardik Prakash]

This reverts commit ef76a3a28c79b628890431aa344af633e892035b.

The patch causes boot regressions on multiple machines. A NULL pointer
dereference occurs when agpio->resource_source.string_ptr is NULL (i.e.
when string_length is 0), and a probe deferral loop causes CPU starvation
leading to kernel panic on Intel CI machines.

The patch needs a proper rewrite addressing these issues before resubmission.

Reported-by: Nathan Chancellor <nathan@kernel.org>
Reported-by: Borah, Chaitanya Kumar <chaitanya.kumar.borah@intel.com>
Signed-off-by: Hardik Prakash <hardikprakash.official@gmail.com>
---
 drivers/i2c/busses/i2c-designware-platdrv.c | 156 --------------------
 1 file changed, 156 deletions(-)

diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index 1c01b0460385..3351c4a9ef11 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -8,8 +8,6 @@
  * Copyright (C) 2007 MontaVista Software Inc.
  * Copyright (C) 2009 Provigent Ltd.
  */
-
-#include <linux/acpi.h>
 #include <linux/clk-provider.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
@@ -132,152 +130,6 @@ static int i2c_dw_probe_lock_support(struct dw_i2c_dev *dev)
 	return 0;
 }
 
-#ifdef CONFIG_ACPI
-struct gpio_dep_ctx {
-	struct list_head gpio_controllers;
-	int ret;
-};
-
-struct gpio_controller_ref {
-	struct list_head node;
-	char *path;
-};
-
-static int check_gpioint_resource(struct acpi_resource *ares, void *data)
-{
-	struct gpio_dep_ctx *ctx = data;
-	struct acpi_resource_gpio *agpio;
-	struct gpio_controller_ref *ref, *tmp;
-	bool found = false;
-
-	if (ares->type != ACPI_RESOURCE_TYPE_GPIO)
-		return 1;
-
-	agpio = &ares->data.gpio;
-	if (agpio->connection_type != ACPI_RESOURCE_GPIO_TYPE_INT)
-		return 1;
-
-	/* Check if we've already tracked this GPIO controller */
-	list_for_each_entry(tmp, &ctx->gpio_controllers, node) {
-		if (!strcmp(tmp->path, agpio->resource_source.string_ptr)) {
-			found = true;
-			break;
-		}
-	}
-
-	if (!found) {
-		ref = kzalloc(sizeof(*ref), GFP_KERNEL);
-		if (!ref) {
-			ctx->ret = -ENOMEM;
-			return 0;
-		}
-
-		ref->path = kstrdup(agpio->resource_source.string_ptr, GFP_KERNEL);
-		if (!ref->path) {
-			kfree(ref);
-			ctx->ret = -ENOMEM;
-			return 0;
-		}
-
-		list_add_tail(&ref->node, &ctx->gpio_controllers);
-	}
-
-	return 1;
-}
-
-static int check_child_gpioint(struct acpi_device *adev, void *data)
-{
-	struct gpio_dep_ctx *ctx = data;
-	struct list_head res_list;
-
-	INIT_LIST_HEAD(&res_list);
-
-	acpi_dev_get_resources(adev, &res_list, check_gpioint_resource, ctx);
-	acpi_dev_free_resource_list(&res_list);
-
-	if (ctx->ret < 0)
-		return ctx->ret;
-
-	return 0;
-}
-
-static int i2c_dw_check_gpio_dependencies(struct device *dev)
-{
-	struct acpi_device *adev = ACPI_COMPANION(dev);
-	struct gpio_dep_ctx ctx = { .ret = 0 };
-	struct gpio_controller_ref *ref, *tmp;
-	int ret = 0;
-
-	if (!adev)
-		return 0;
-
-	INIT_LIST_HEAD(&ctx.gpio_controllers);
-
-	/* Walk all child devices and collect GpioInt controller references */
-	ret = acpi_dev_for_each_child(adev, check_child_gpioint, &ctx);
-	if (ret < 0 || ctx.ret < 0) {
-		ret = ctx.ret ?: ret;
-		goto cleanup;
-	}
-
-	/* For each GPIO controller, check if its parent device is bound */
-	list_for_each_entry(ref, &ctx.gpio_controllers, node) {
-		acpi_handle handle;
-		acpi_status status;
-		struct acpi_device *gpio_adev;
-		struct device *gpio_dev;
-		bool bound;
-
-		status = acpi_get_handle(NULL, ref->path, &handle);
-		if (ACPI_FAILURE(status))
-			continue;
-
-		gpio_adev = acpi_fetch_acpi_dev(handle);
-		if (!gpio_adev)
-			continue;
-
-		gpio_dev = acpi_get_first_physical_node(gpio_adev);
-		acpi_dev_put(gpio_adev);
-
-		if (!gpio_dev) {
-			ret = -EPROBE_DEFER;
-			goto cleanup;
-		}
-
-		/*
-		 * Check if the GPIO controller's device is bound. If not,
-		 * defer probe to ensure GPIO initialization (including IRQ
-		 * setup and quirks) is complete before we enumerate I2C
-		 * child devices.
-		 */
-		scoped_guard(device, gpio_dev) {
-			bound = device_is_bound(gpio_dev);
-		}
-		if (!bound) {
-			put_device(gpio_dev);
-			ret = -EPROBE_DEFER;
-			goto cleanup;
-		}
-
-		put_device(gpio_dev);
-	}
-
-cleanup:
-	list_for_each_entry_safe(ref, tmp, &ctx.gpio_controllers, node) {
-		list_del(&ref->node);
-		kfree(ref->path);
-		kfree(ref);
-	}
-
-	return ret;
-}
-#else
-static int i2c_dw_check_gpio_dependencies(struct device *dev)
-{
-	return 0;
-}
-#endif /* CONFIG_ACPI */
-
 static int dw_i2c_plat_probe(struct platform_device *pdev)
 {
 	u32 flags = (uintptr_t)device_get_match_data(&pdev->dev);
@@ -286,14 +138,6 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
 	struct dw_i2c_dev *dev;
 	int irq, ret;
 
-	/*
-	 * Check if any child devices have GpioInt resources, and if so,
-	 * defer probe until those GPIO controllers are fully bound.
-	 */
-	ret = i2c_dw_check_gpio_dependencies(device);
-	if (ret)
-		return ret;
-
 	irq = platform_get_irq_optional(pdev, 0);
 	if (irq == -ENXIO)
 		flags |= ACCESS_POLLING;

base-commit: 3f786abd23951f3f600a62fef42469d9200d5f52
prerequisite-patch-id: 22fa9ba20fa28cf94185281704c51feef7abc701
-- 
2.54.0

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

[Andy Shevchenko]

On Wed, Jun 10, 2026 at 02:07:01PM +0530, Hardik Prakash wrote:
> This reverts commit ef76a3a28c79b628890431aa344af633e892035b.
> 
> The patch causes boot regressions on multiple machines. A NULL pointer
> dereference occurs when agpio->resource_source.string_ptr is NULL (i.e.
> when string_length is 0), and a probe deferral loop causes CPU starvation
> leading to kernel panic on Intel CI machines.
> 
> The patch needs a proper rewrite addressing these issues before resubmission.

Yes, please apply this (whoever is the right maintainer to do so).
Acked-by: Andy Shevchenko <andriy.shevchenko@intel.com>

-- 
With Best Regards,
Andy Shevchenko

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

[Borah, Chaitanya Kumar]

On 6/10/2026 2:07 PM, Hardik Prakash wrote:
> This reverts commit ef76a3a28c79b628890431aa344af633e892035b.
> 
> The patch causes boot regressions on multiple machines. A NULL pointer
> dereference occurs when agpio->resource_source.string_ptr is NULL (i.e.
> when string_length is 0), and a probe deferral loop causes CPU starvation
> leading to kernel panic on Intel CI machines.
> 
> The patch needs a proper rewrite addressing these issues before resubmission.
> 
> Reported-by: Nathan Chancellor <nathan@kernel.org>
> Reported-by: Borah, Chaitanya Kumar <chaitanya.kumar.borah@intel.com>
> Signed-off-by: Hardik Prakash <hardikprakash.official@gmail.com>

Perhaps needs

Closes: 
https://lore.kernel.org/linux-i2c/90656be5-eca0-4a09-9b19-0c6e85f1d455@intel.com/

Feel free to use.

Tested-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>


> ---
>   drivers/i2c/busses/i2c-designware-platdrv.c | 156 --------------------
>   1 file changed, 156 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
> index 1c01b0460385..3351c4a9ef11 100644
> --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> @@ -8,8 +8,6 @@
>    * Copyright (C) 2007 MontaVista Software Inc.
>    * Copyright (C) 2009 Provigent Ltd.
>    */
> -
> -#include <linux/acpi.h>
>   #include <linux/clk-provider.h>
>   #include <linux/clk.h>
>   #include <linux/delay.h>
> @@ -132,152 +130,6 @@ static int i2c_dw_probe_lock_support(struct dw_i2c_dev *dev)
>   	return 0;
>   }
>   
> -#ifdef CONFIG_ACPI
> -struct gpio_dep_ctx {
> -	struct list_head gpio_controllers;
> -	int ret;
> -};
> -
> -struct gpio_controller_ref {
> -	struct list_head node;
> -	char *path;
> -};
> -
> -static int check_gpioint_resource(struct acpi_resource *ares, void *data)
> -{
> -	struct gpio_dep_ctx *ctx = data;
> -	struct acpi_resource_gpio *agpio;
> -	struct gpio_controller_ref *ref, *tmp;
> -	bool found = false;
> -
> -	if (ares->type != ACPI_RESOURCE_TYPE_GPIO)
> -		return 1;
> -
> -	agpio = &ares->data.gpio;
> -	if (agpio->connection_type != ACPI_RESOURCE_GPIO_TYPE_INT)
> -		return 1;
> -
> -	/* Check if we've already tracked this GPIO controller */
> -	list_for_each_entry(tmp, &ctx->gpio_controllers, node) {
> -		if (!strcmp(tmp->path, agpio->resource_source.string_ptr)) {
> -			found = true;
> -			break;
> -		}
> -	}
> -
> -	if (!found) {
> -		ref = kzalloc(sizeof(*ref), GFP_KERNEL);
> -		if (!ref) {
> -			ctx->ret = -ENOMEM;
> -			return 0;
> -		}
> -
> -		ref->path = kstrdup(agpio->resource_source.string_ptr, GFP_KERNEL);
> -		if (!ref->path) {
> -			kfree(ref);
> -			ctx->ret = -ENOMEM;
> -			return 0;
> -		}
> -
> -		list_add_tail(&ref->node, &ctx->gpio_controllers);
> -	}
> -
> -	return 1;
> -}
> -
> -static int check_child_gpioint(struct acpi_device *adev, void *data)
> -{
> -	struct gpio_dep_ctx *ctx = data;
> -	struct list_head res_list;
> -
> -	INIT_LIST_HEAD(&res_list);
> -
> -	acpi_dev_get_resources(adev, &res_list, check_gpioint_resource, ctx);
> -	acpi_dev_free_resource_list(&res_list);
> -
> -	if (ctx->ret < 0)
> -		return ctx->ret;
> -
> -	return 0;
> -}
> -
> -static int i2c_dw_check_gpio_dependencies(struct device *dev)
> -{
> -	struct acpi_device *adev = ACPI_COMPANION(dev);
> -	struct gpio_dep_ctx ctx = { .ret = 0 };
> -	struct gpio_controller_ref *ref, *tmp;
> -	int ret = 0;
> -
> -	if (!adev)
> -		return 0;
> -
> -	INIT_LIST_HEAD(&ctx.gpio_controllers);
> -
> -	/* Walk all child devices and collect GpioInt controller references */
> -	ret = acpi_dev_for_each_child(adev, check_child_gpioint, &ctx);
> -	if (ret < 0 || ctx.ret < 0) {
> -		ret = ctx.ret ?: ret;
> -		goto cleanup;
> -	}
> -
> -	/* For each GPIO controller, check if its parent device is bound */
> -	list_for_each_entry(ref, &ctx.gpio_controllers, node) {
> -		acpi_handle handle;
> -		acpi_status status;
> -		struct acpi_device *gpio_adev;
> -		struct device *gpio_dev;
> -		bool bound;
> -
> -		status = acpi_get_handle(NULL, ref->path, &handle);
> -		if (ACPI_FAILURE(status))
> -			continue;
> -
> -		gpio_adev = acpi_fetch_acpi_dev(handle);
> -		if (!gpio_adev)
> -			continue;
> -
> -		gpio_dev = acpi_get_first_physical_node(gpio_adev);
> -		acpi_dev_put(gpio_adev);
> -
> -		if (!gpio_dev) {
> -			ret = -EPROBE_DEFER;
> -			goto cleanup;
> -		}
> -
> -		/*
> -		 * Check if the GPIO controller's device is bound. If not,
> -		 * defer probe to ensure GPIO initialization (including IRQ
> -		 * setup and quirks) is complete before we enumerate I2C
> -		 * child devices.
> -		 */
> -		scoped_guard(device, gpio_dev) {
> -			bound = device_is_bound(gpio_dev);
> -		}
> -		if (!bound) {
> -			put_device(gpio_dev);
> -			ret = -EPROBE_DEFER;
> -			goto cleanup;
> -		}
> -
> -		put_device(gpio_dev);
> -	}
> -
> -cleanup:
> -	list_for_each_entry_safe(ref, tmp, &ctx.gpio_controllers, node) {
> -		list_del(&ref->node);
> -		kfree(ref->path);
> -		kfree(ref);
> -	}
> -
> -	return ret;
> -}
> -#else
> -static int i2c_dw_check_gpio_dependencies(struct device *dev)
> -{
> -	return 0;
> -}
> -#endif /* CONFIG_ACPI */
> -
>   static int dw_i2c_plat_probe(struct platform_device *pdev)
>   {
>   	u32 flags = (uintptr_t)device_get_match_data(&pdev->dev);
> @@ -286,14 +138,6 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
>   	struct dw_i2c_dev *dev;
>   	int irq, ret;
>   
> -	/*
> -	 * Check if any child devices have GpioInt resources, and if so,
> -	 * defer probe until those GPIO controllers are fully bound.
> -	 */
> -	ret = i2c_dw_check_gpio_dependencies(device);
> -	if (ret)
> -		return ret;
> -
>   	irq = platform_get_irq_optional(pdev, 0);
>   	if (irq == -ENXIO)
>   		flags |= ACCESS_POLLING;
> 
> base-commit: 3f786abd23951f3f600a62fef42469d9200d5f52
> prerequisite-patch-id: 22fa9ba20fa28cf94185281704c51feef7abc701

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

[Nathan Chancellor]

On Wed, Jun 10, 2026 at 02:07:01PM +0530, Hardik Prakash wrote:
> This reverts commit ef76a3a28c79b628890431aa344af633e892035b.
> 
> The patch causes boot regressions on multiple machines. A NULL pointer
> dereference occurs when agpio->resource_source.string_ptr is NULL (i.e.
> when string_length is 0), and a probe deferral loop causes CPU starvation
> leading to kernel panic on Intel CI machines.
> 
> The patch needs a proper rewrite addressing these issues before resubmission.
> 
> Reported-by: Nathan Chancellor <nathan@kernel.org>
> Reported-by: Borah, Chaitanya Kumar <chaitanya.kumar.borah@intel.com>
> Signed-off-by: Hardik Prakash <hardikprakash.official@gmail.com>

Closes: https://lore.kernel.org/20260602185339.GA404948@ax162/
Tested-by: Nathan Chancellor <nathan@kernel.org>

> ---
>  drivers/i2c/busses/i2c-designware-platdrv.c | 156 --------------------
>  1 file changed, 156 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
> index 1c01b0460385..3351c4a9ef11 100644
> --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> @@ -8,8 +8,6 @@
>   * Copyright (C) 2007 MontaVista Software Inc.
>   * Copyright (C) 2009 Provigent Ltd.
>   */
> -
> -#include <linux/acpi.h>
>  #include <linux/clk-provider.h>
>  #include <linux/clk.h>
>  #include <linux/delay.h>
> @@ -132,152 +130,6 @@ static int i2c_dw_probe_lock_support(struct dw_i2c_dev *dev)
>  	return 0;
>  }
>  
> -#ifdef CONFIG_ACPI
> -struct gpio_dep_ctx {
> -	struct list_head gpio_controllers;
> -	int ret;
> -};
> -
> -struct gpio_controller_ref {
> -	struct list_head node;
> -	char *path;
> -};
> -
> -static int check_gpioint_resource(struct acpi_resource *ares, void *data)
> -{
> -	struct gpio_dep_ctx *ctx = data;
> -	struct acpi_resource_gpio *agpio;
> -	struct gpio_controller_ref *ref, *tmp;
> -	bool found = false;
> -
> -	if (ares->type != ACPI_RESOURCE_TYPE_GPIO)
> -		return 1;
> -
> -	agpio = &ares->data.gpio;
> -	if (agpio->connection_type != ACPI_RESOURCE_GPIO_TYPE_INT)
> -		return 1;
> -
> -	/* Check if we've already tracked this GPIO controller */
> -	list_for_each_entry(tmp, &ctx->gpio_controllers, node) {
> -		if (!strcmp(tmp->path, agpio->resource_source.string_ptr)) {
> -			found = true;
> -			break;
> -		}
> -	}
> -
> -	if (!found) {
> -		ref = kzalloc(sizeof(*ref), GFP_KERNEL);
> -		if (!ref) {
> -			ctx->ret = -ENOMEM;
> -			return 0;
> -		}
> -
> -		ref->path = kstrdup(agpio->resource_source.string_ptr, GFP_KERNEL);
> -		if (!ref->path) {
> -			kfree(ref);
> -			ctx->ret = -ENOMEM;
> -			return 0;
> -		}
> -
> -		list_add_tail(&ref->node, &ctx->gpio_controllers);
> -	}
> -
> -	return 1;
> -}
> -
> -static int check_child_gpioint(struct acpi_device *adev, void *data)
> -{
> -	struct gpio_dep_ctx *ctx = data;
> -	struct list_head res_list;
> -
> -	INIT_LIST_HEAD(&res_list);
> -
> -	acpi_dev_get_resources(adev, &res_list, check_gpioint_resource, ctx);
> -	acpi_dev_free_resource_list(&res_list);
> -
> -	if (ctx->ret < 0)
> -		return ctx->ret;
> -
> -	return 0;
> -}
> -
> -static int i2c_dw_check_gpio_dependencies(struct device *dev)
> -{
> -	struct acpi_device *adev = ACPI_COMPANION(dev);
> -	struct gpio_dep_ctx ctx = { .ret = 0 };
> -	struct gpio_controller_ref *ref, *tmp;
> -	int ret = 0;
> -
> -	if (!adev)
> -		return 0;
> -
> -	INIT_LIST_HEAD(&ctx.gpio_controllers);
> -
> -	/* Walk all child devices and collect GpioInt controller references */
> -	ret = acpi_dev_for_each_child(adev, check_child_gpioint, &ctx);
> -	if (ret < 0 || ctx.ret < 0) {
> -		ret = ctx.ret ?: ret;
> -		goto cleanup;
> -	}
> -
> -	/* For each GPIO controller, check if its parent device is bound */
> -	list_for_each_entry(ref, &ctx.gpio_controllers, node) {
> -		acpi_handle handle;
> -		acpi_status status;
> -		struct acpi_device *gpio_adev;
> -		struct device *gpio_dev;
> -		bool bound;
> -
> -		status = acpi_get_handle(NULL, ref->path, &handle);
> -		if (ACPI_FAILURE(status))
> -			continue;
> -
> -		gpio_adev = acpi_fetch_acpi_dev(handle);
> -		if (!gpio_adev)
> -			continue;
> -
> -		gpio_dev = acpi_get_first_physical_node(gpio_adev);
> -		acpi_dev_put(gpio_adev);
> -
> -		if (!gpio_dev) {
> -			ret = -EPROBE_DEFER;
> -			goto cleanup;
> -		}
> -
> -		/*
> -		 * Check if the GPIO controller's device is bound. If not,
> -		 * defer probe to ensure GPIO initialization (including IRQ
> -		 * setup and quirks) is complete before we enumerate I2C
> -		 * child devices.
> -		 */
> -		scoped_guard(device, gpio_dev) {
> -			bound = device_is_bound(gpio_dev);
> -		}
> -		if (!bound) {
> -			put_device(gpio_dev);
> -			ret = -EPROBE_DEFER;
> -			goto cleanup;
> -		}
> -
> -		put_device(gpio_dev);
> -	}
> -
> -cleanup:
> -	list_for_each_entry_safe(ref, tmp, &ctx.gpio_controllers, node) {
> -		list_del(&ref->node);
> -		kfree(ref->path);
> -		kfree(ref);
> -	}
> -
> -	return ret;
> -}
> -#else
> -static int i2c_dw_check_gpio_dependencies(struct device *dev)
> -{
> -	return 0;
> -}
> -#endif /* CONFIG_ACPI */
> -
>  static int dw_i2c_plat_probe(struct platform_device *pdev)
>  {
>  	u32 flags = (uintptr_t)device_get_match_data(&pdev->dev);
> @@ -286,14 +138,6 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
>  	struct dw_i2c_dev *dev;
>  	int irq, ret;
>  
> -	/*
> -	 * Check if any child devices have GpioInt resources, and if so,
> -	 * defer probe until those GPIO controllers are fully bound.
> -	 */
> -	ret = i2c_dw_check_gpio_dependencies(device);
> -	if (ret)
> -		return ret;
> -
>  	irq = platform_get_irq_optional(pdev, 0);
>  	if (irq == -ENXIO)
>  		flags |= ACCESS_POLLING;
> 
> base-commit: 3f786abd23951f3f600a62fef42469d9200d5f52
> prerequisite-patch-id: 22fa9ba20fa28cf94185281704c51feef7abc701
> -- 
> 2.54.0
> 

-- 
Cheers,
Nathan

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

[Andi Shyti]

Hi Linus,

On Wed, Jun 10, 2026 at 02:07:01PM +0530, Hardik Prakash wrote:
> This reverts commit ef76a3a28c79b628890431aa344af633e892035b.

Is this in your branch?

Thanks,
Andi

> The patch causes boot regressions on multiple machines. A NULL pointer
> dereference occurs when agpio->resource_source.string_ptr is NULL (i.e.
> when string_length is 0), and a probe deferral loop causes CPU starvation
> leading to kernel panic on Intel CI machines.
> 
> The patch needs a proper rewrite addressing these issues before resubmission.
> 
> Reported-by: Nathan Chancellor <nathan@kernel.org>
> Reported-by: Borah, Chaitanya Kumar <chaitanya.kumar.borah@intel.com>
> Signed-off-by: Hardik Prakash <hardikprakash.official@gmail.com>

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

[Andy Shevchenko]

On Sun, Jun 14, 2026 at 11:56:55PM +0200, Andi Shyti wrote:
> Hi Linus,
> 
> On Wed, Jun 10, 2026 at 02:07:01PM +0530, Hardik Prakash wrote:
> > This reverts commit ef76a3a28c79b628890431aa344af633e892035b.
> 
> Is this in your branch?

$ git tag --contains ef76a3a28c79b6288
next-20260601
next-20260602
next-20260603
next-20260604
next-20260605
next-20260608
next-20260609
next-20260610
next-20260611

> > The patch causes boot regressions on multiple machines. A NULL pointer
> > dereference occurs when agpio->resource_source.string_ptr is NULL (i.e.
> > when string_length is 0), and a probe deferral loop causes CPU starvation
> > leading to kernel panic on Intel CI machines.
> > 
> > The patch needs a proper rewrite addressing these issues before resubmission.

-- 
With Best Regards,
Andy Shevchenko

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

[Andi Shyti]

Hi Andy,

> > > This reverts commit ef76a3a28c79b628890431aa344af633e892035b.
> > 
> > Is this in your branch?
> 
> $ git tag --contains ef76a3a28c79b6288
> next-20260601
> next-20260602
> next-20260603
> next-20260604
> next-20260605
> next-20260608
> next-20260609
> next-20260610
> next-20260611

Yes, but I'm not finding out how it got there. I only see it in
one of Wolfram's branches, but I don't think it came in that way.

I can merge this revert as well, but only after the original
patch hits mainline.

Andi

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

[Wolfram Sang]

[-- Attachment #1: Type: text/plain, Size: 542 bytes --]


> > $ git tag --contains ef76a3a28c79b6288
> > next-20260601
> > next-20260602
> > next-20260603
> > next-20260604
> > next-20260605
> > next-20260608
> > next-20260609
> > next-20260610
> > next-20260611
> 
> Yes, but I'm not finding out how it got there. I only see it in
> one of Wolfram's branches, but I don't think it came in that way.

IIRC I asked Linus Walleij to handle this via the GPIO tree because the
proper fix landed there and the I2C addition was a mere cleanup from a
previous attempt to fix the issue.


[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

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

[Linus Walleij]

On Mon, Jun 15, 2026 at 1:11 PM Wolfram Sang
<wsa+renesas@sang-engineering.com> wrote:

> > > $ git tag --contains ef76a3a28c79b6288
> > > next-20260601
> > > next-20260602
> > > next-20260603
> > > next-20260604
> > > next-20260605
> > > next-20260608
> > > next-20260609
> > > next-20260610
> > > next-20260611
> >
> > Yes, but I'm not finding out how it got there. I only see it in
> > one of Wolfram's branches, but I don't think it came in that way.
>
> IIRC I asked Linus Walleij to handle this via the GPIO tree because the
> proper fix landed there and the I2C addition was a mere cleanup from a
> previous attempt to fix the issue.

So this revert is not in my tree because it isn't needed: I never
sent the patch it is reverting to Torvalds to begin with. I even mentioned
this in my pull request to him: by being so lazy in sending my fixes
upstream I avoided the whole ordeal. Maybe I should always be lazy.

Yours,
Linus Walleij

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

[Linus Walleij]

On Sun, Jun 14, 2026 at 11:57 PM Andi Shyti <andi.shyti@kernel.org> wrote:

> On Wed, Jun 10, 2026 at 02:07:01PM +0530, Hardik Prakash wrote:
> > This reverts commit ef76a3a28c79b628890431aa344af633e892035b.
>
> Is this in your branch?

Nope. It was too late for me to handle as fix, what was merged for fixes was
this:

commit 3f786abd23951f3f600a62fef42469d9200d5f52
Author: Hardik Prakash <hardikprakash.official@gmail.com>
Date:   Fri May 29 15:38:36 2026 +0530

    Revert "pinctrl-amd: enable IRQ for WACF2200 touchscreen on Lenovo
Yoga 7 14AGP11"

    This reverts commit 3812a9e84265a5cdd90d29fe8d97a023e91fb945.

This needs to go through the i2c tree at this point.

Yours,
Linus Walleij