linux-kernel - [PATCH v3 1/6] platform/x86: lenovo-wmi-helpers: Convert returned 4B buffer into u32

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Message-ID: <20251031155349.24693-2-i@rong.moe>
Date: Fri, 31 Oct 2025 23:51:51 +0800
From: Rong Zhang <i@...g.moe>
To: Mark Pearson <mpearson-lenovo@...ebb.ca>,
	"Derek J. Clark" <derekjohn.clark@...il.com>,
	Armin Wolf <W_Armin@....de>,
	Hans de Goede <hansg@...nel.org>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc: Rong Zhang <i@...g.moe>,
	Guenter Roeck <linux@...ck-us.net>,
	platform-driver-x86@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-hwmon@...r.kernel.org
Subject: [PATCH v3 1/6] platform/x86: lenovo-wmi-helpers: Convert returned 4B buffer into u32

The Windows WMI-ACPI driver converts all ACPI objects into a common
buffer format, so returning a buffer with four bytes will look like an
integer for WMI consumers under Windows.

Therefore, some devices may simply implement the corresponding ACPI
methods to always return a buffer. While lwmi_dev_evaluate_int() expects
an integer (u32), convert returned 4-byte buffer into u32 to support
these devices.

Suggested-by: Armin Wolf <W_Armin@....de>
Link: https://lore.kernel.org/r/f1787927-b655-4321-b9d9-bc12353c72db@gmx.de/
Signed-off-by: Rong Zhang <i@...g.moe>
Reviewed-by: Derek J. Clark <derekjohn.clark@...il.com>
Tested-by: Derek J. Clark <derekjohn.clark@...il.com>
---
Changes in v2:
- New patch (thanks Armin Wolf)
---
 drivers/platform/x86/lenovo/wmi-helpers.c | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/platform/x86/lenovo/wmi-helpers.c b/drivers/platform/x86/lenovo/wmi-helpers.c
index f6fef6296251..f3bc92ac505a 100644
--- a/drivers/platform/x86/lenovo/wmi-helpers.c
+++ b/drivers/platform/x86/lenovo/wmi-helpers.c
@@ -59,10 +59,25 @@ int lwmi_dev_evaluate_int(struct wmi_device *wdev, u8 instance, u32 method_id,
 		if (!ret_obj)
 			return -ENODATA;
 
-		if (ret_obj->type != ACPI_TYPE_INTEGER)
-			return -ENXIO;
+		switch (ret_obj->type) {
+		/*
+		 * The ACPI method may simply return a 4-byte buffer when a u32
+		 * integer is expected. This is valid on Windows as its WMI-ACPI
+		 * driver converts everything to a common buffer.
+		 */
+		case ACPI_TYPE_BUFFER: {
+			if (ret_obj->buffer.length != 4)
+				return -ENXIO;
 
-		*retval = (u32)ret_obj->integer.value;
+			*retval = *((u32 *)ret_obj->buffer.pointer);
+			return 0;
+		}
+		case ACPI_TYPE_INTEGER:
+			*retval = (u32)ret_obj->integer.value;
+			return 0;
+		default:
+			return -ENXIO;
+		}
 	}
 
 	return 0;
-- 
2.51.0