diff mbox series

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

Message ID 20250203182322.384883-4-W_Armin@gmx.de (mailing list archive)
State Superseded, archived
Headers show
Series platform/x86: wmi: Rework WMI device enabling | expand

Commit Message

Armin Wolf Feb. 3, 2025, 6:23 p.m. UTC 
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@gmx.de>
---
 drivers/platform/x86/think-lmi.c | 23 +++++++++--------------
 drivers/platform/x86/think-lmi.h |  2 ++
 2 files changed, 11 insertions(+), 14 deletions(-)

--
2.39.5

Comments

Ilpo Järvinen Feb. 13, 2025, 1:17 p.m. UTC | #1 
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@gmx.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?
Armin Wolf Feb. 14, 2025, 3:07 a.m. UTC | #2 
Am 13.02.25 um 14:17 schrieb Ilpo Järvinen:

> 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@gmx.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?
>
Hi,

the reason why wmidev_block_query() only returns NULL in case of an error is that
according to the WMI-ACPI specification, querying a WMI data block should return data.

So we have two error scenarios:

- ACPI error => firmware error => EIO
- no data returned => violation of firmware spec => EIO

Because of this always returning EIO is the correct approach in my opinion.

Thanks,
Armin Wolf
diff mbox series

Patch

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;

 	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;