linux-kernel - Re: [PATCH 3/7] platform/x86: think-lmi: Use WMI bus API when accessing BIOS settings

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Message-ID: <0dd7bda3-bf76-228b-27f3-f057e80e3a03@linux.intel.com>
Date: Thu, 13 Feb 2025 15:17:03 +0200 (EET)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Armin Wolf <W_Armin@....de>
cc: james@...iv.tech, markpearson@...ovo.com, jorge.lopez2@...com, 
    jdelvare@...e.com, linux@...ck-us.net, linux-hwmon@...r.kernel.org, 
    LKML <linux-kernel@...r.kernel.org>, Hans de Goede <hdegoede@...hat.com>, 
    platform-driver-x86@...r.kernel.org, corbet@....net, 
    linux-doc@...r.kernel.org
Subject: Re: [PATCH 3/7] platform/x86: think-lmi: Use WMI bus API when
 accessing BIOS settings

On Mon, 3 Feb 2025, Armin Wolf wrote:

> Since the driver already binds to LENOVO_BIOS_SETTING_GUID, using
> wmidev_block_query() inside tlmi_setting() allows for faster
> access to BIOS settings.
> 
> Signed-off-by: Armin Wolf <W_Armin@....de>
> ---
>  drivers/platform/x86/think-lmi.c | 23 +++++++++--------------
>  drivers/platform/x86/think-lmi.h |  2 ++
>  2 files changed, 11 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/platform/x86/think-lmi.c b/drivers/platform/x86/think-lmi.c
> index 2c94a4af9a1d..0fc275e461be 100644
> --- a/drivers/platform/x86/think-lmi.c
> +++ b/drivers/platform/x86/think-lmi.c
> @@ -344,20 +344,14 @@ static int tlmi_opcode_setting(char *setting, const char *value)
>  	return ret;
>  }
> 
> -static int tlmi_setting(int item, char **value, const char *guid_string)
> +static int tlmi_setting(struct wmi_device *wdev, int item, char **value)
>  {
> -	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
>  	union acpi_object *obj;
> -	acpi_status status;
>  	int ret;
> 
> -	status = wmi_query_block(guid_string, item, &output);
> -	if (ACPI_FAILURE(status))
> -		return -EIO;
> -
> -	obj = output.pointer;
> +	obj = wmidev_block_query(wdev, item);
>  	if (!obj)
> -		return -ENODATA;
> +		return -EIO;

Hi Armin,

I'm trying to understand why there are these back and forth changes in the 
error code.

It almost looks to me like wmidev_block_query() would want to return the 
error code itself because after you abstracted this code using 
wmidev_block_query(), you had to change the error code because you no 
longer have access to the key detail to decide which error code should be 
returned. That is, use ERR_PTR() inside wmidev_block_query() and the 
callers should just pass that error code on with IS_ERR & friends?

-- 
 i.

>  	ret = tlmi_extract_output_string(obj, value);
>  	kfree(obj);
> @@ -995,7 +989,7 @@ static ssize_t current_value_show(struct kobject *kobj, struct kobj_attribute *a
>  	char *item, *value;
>  	int ret;
> 
> -	ret = tlmi_setting(setting->index, &item, LENOVO_BIOS_SETTING_GUID);
> +	ret = tlmi_setting(setting->wdev, setting->index, &item);
>  	if (ret)
>  		return ret;
> 
> @@ -1588,7 +1582,7 @@ static struct tlmi_pwd_setting *tlmi_create_auth(const char *pwd_type,
>  	return new_pwd;
>  }
> 
> -static int tlmi_analyze(void)
> +static int tlmi_analyze(struct wmi_device *wdev)
>  {
>  	int i, ret;
> 
> @@ -1625,7 +1619,7 @@ static int tlmi_analyze(void)
>  		char *item = NULL;
> 
>  		tlmi_priv.setting[i] = NULL;
> -		ret = tlmi_setting(i, &item, LENOVO_BIOS_SETTING_GUID);
> +		ret = tlmi_setting(wdev, i, &item);
>  		if (ret)
>  			break;
>  		if (!item)
> @@ -1648,6 +1642,7 @@ static int tlmi_analyze(void)
>  			kfree(item);
>  			goto fail_clear_attr;
>  		}
> +		setting->wdev = wdev;
>  		setting->index = i;
>  		strscpy(setting->display_name, item);
>  		/* If BIOS selections supported, load those */
> @@ -1666,7 +1661,7 @@ static int tlmi_analyze(void)
>  			 */
>  			char *optitem, *optstart, *optend;
> 
> -			if (!tlmi_setting(setting->index, &optitem, LENOVO_BIOS_SETTING_GUID)) {
> +			if (!tlmi_setting(setting->wdev, setting->index, &optitem)) {
>  				optstart = strstr(optitem, "[Optional:");
>  				if (optstart) {
>  					optstart += strlen("[Optional:");
> @@ -1791,7 +1786,7 @@ static int tlmi_probe(struct wmi_device *wdev, const void *context)
>  {
>  	int ret;
> 
> -	ret = tlmi_analyze();
> +	ret = tlmi_analyze(wdev);
>  	if (ret)
>  		return ret;
> 
> diff --git a/drivers/platform/x86/think-lmi.h b/drivers/platform/x86/think-lmi.h
> index f267d8b46957..a80452482227 100644
> --- a/drivers/platform/x86/think-lmi.h
> +++ b/drivers/platform/x86/think-lmi.h
> @@ -4,6 +4,7 @@
>  #define _THINK_LMI_H_
> 
>  #include <linux/types.h>
> +#include <linux/wmi.h>
> 
>  #define TLMI_SETTINGS_COUNT  256
>  #define TLMI_SETTINGS_MAXLEN 512
> @@ -87,6 +88,7 @@ struct tlmi_pwd_setting {
>  /* Attribute setting details */
>  struct tlmi_attr_setting {
>  	struct kobject kobj;
> +	struct wmi_device *wdev;
>  	int index;
>  	char display_name[TLMI_SETTINGS_MAXLEN];
>  	char *possible_values;
> --
> 2.39.5
>