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

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Message-ID: <8ec638c2-93b6-48e4-8ac4-965072b1d5af@roeck-us.net>
Date: Wed, 21 Feb 2024 09:34:54 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Michael Brunner <michael.brunner@...tron.com>,
 "lee.jones@...aro.org" <lee.jones@...aro.org>
Cc: "mibru@....de" <mibru@....de>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mfd: kempld-core: don't replace resources provided by
 ACPI

On 2/21/24 09:10, Michael Brunner wrote:
> 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@...tron.com>

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

> ---
>   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;
>   }