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

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

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