[PATCH] mfd: kempld-core: don't replace resources provided by ACPI

[Michael Brunner]

The current implementation to retrieve ACPI resources is faulty
and may cause issues that even can lead to non-booting systems.

When adding data from an ACPI device, the resources are already
assigned to the platform device. Therefore there is no need to
retrieve the resource list from ACPI and manually assign it to
the platform device. Also there shouldn't be any BIOS in the wild
anymore, that does not have resources added to the KEMPLD ACPI
data.

In particular this fixes an issue where the retrieval of the
resource list using /proc/ioports is disturbed and does not list
the assigned resource for the kempld device or even no resources
at all.
On some distributions this also leads to problems during system
initialization (e.g. with udev) and causes the system to not
boot at all.

I have reproduced the issue with the following kernel versions:
    5.10.209
    5.15.148
    6.1.25
    6.6.17
    6.7.5
    6.8-rc5

The patch applies to all of those versions and seems to resolve
the issue.

Signed-off-by: Michael Brunner <michael.brunner@xxxxxxxxxxx>
---
 drivers/mfd/kempld-core.c | 37 -------------------------------------
 1 file changed, 37 deletions(-)

diff --git a/drivers/mfd/kempld-core.c b/drivers/mfd/kempld-core.c
index 67af36a38913..5557f023a173 100644
--- a/drivers/mfd/kempld-core.c
+++ b/drivers/mfd/kempld-core.c
@@ -428,50 +428,13 @@ static int kempld_detect_device(struct kempld_device_data *pld)
 #ifdef CONFIG_ACPI
 static int kempld_get_acpi_data(struct platform_device *pdev)
 {
-	struct list_head resource_list;
-	struct resource *resources;
-	struct resource_entry *rentry;
 	struct device *dev = &pdev->dev;
-	struct acpi_device *acpi_dev = ACPI_COMPANION(dev);
 	const struct kempld_platform_data *pdata;
 	int ret;
-	int count;
 
 	pdata = acpi_device_get_match_data(dev);
 	ret = platform_device_add_data(pdev, pdata,
 				       sizeof(struct kempld_platform_data));
-	if (ret)
-		return ret;
-
-	INIT_LIST_HEAD(&resource_list);
-	ret = acpi_dev_get_resources(acpi_dev, &resource_list, NULL, NULL);
-	if (ret < 0)
-		goto out;
-
-	count = ret;
-
-	if (count == 0) {
-		ret = platform_device_add_resources(pdev, pdata->ioresource, 1);
-		goto out;
-	}
-
-	resources = devm_kcalloc(&acpi_dev->dev, count, sizeof(*resources),
-				 GFP_KERNEL);
-	if (!resources) {
-		ret = -ENOMEM;
-		goto out;
-	}
-
-	count = 0;
-	list_for_each_entry(rentry, &resource_list, node) {
-		memcpy(&resources[count], rentry->res,
-		       sizeof(*resources));
-		count++;
-	}
-	ret = platform_device_add_resources(pdev, resources, count);
-
-out:
-	acpi_dev_free_resource_list(&resource_list);
 
 	return ret;
 }
-- 
2.25.1