Unverified Commit 465dc9da authored Jan 21, 2026 by Rong Zhang Committed by Ilpo Järvinen Jan 21, 2026

platform/x86: lenovo-wmi-helpers: Convert returned 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 >=4B buffer into u32 to support these
devices.

Suggested-by: Armin Wolf <W_Armin@gmx.de>
Link: https://lore.kernel.org/r/f1787927-b655-4321-b9d9-bc12353c72db@gmx.de/


Signed-off-by: Rong Zhang <i@rong.moe>
Reviewed-by: Derek J. Clark <derekjohn.clark@gmail.com>
Tested-by: Derek J. Clark <derekjohn.clark@gmail.com>
Reviewed-by: Armin Wolf <W_Armin@gmx.de>
Link: https://patch.msgid.link/20260120182104.163424-2-i@rong.moe


Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

parent 2177a022

drivers/platform/x86/lenovo/wmi-helpers.c

+18 −3

Original line number	Diff line number	Diff line
		@@ -21,6 +21,7 @@
		#include <linux/errno.h>
		#include <linux/export.h>
		#include <linux/module.h>
		#include <linux/unaligned.h>
		#include <linux/wmi.h>

		#include "wmi-helpers.h"
		@@ -59,10 +60,24 @@ 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)
		switch (ret_obj->type) {
		/*
		* The ACPI method may simply return a buffer when a u32
		* 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 < sizeof(u32))
		return -ENXIO;

		*retval = get_unaligned_le32(ret_obj->buffer.pointer);
		return 0;
		case ACPI_TYPE_INTEGER:
		*retval = (u32)ret_obj->integer.value;
		return 0;
		default:
		return -ENXIO;
		}
		}

		return 0;