[PATCH v9 1/2] Revert "i2c: designware: defer probe if child GpioInt controllers are not bound"

[Hardik Prakash <hardikprakash.official@gmail.com>]

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>
Acked-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Tested-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Closes: https://lore.kernel.org/linux-i2c/90656be5-eca0-4a09-9b19-0c6e85f1d455@intel.com/
Closes: https://lore.kernel.org/20260602185339.GA404948@ax162/
---
 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;
-- 
2.54.0