On Thu, Oct 30, 2025 at 12:40 PM Rong Zhang <i@rong.moe> wrote:
>
> 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@gmx.de>
> Link: https://lore.kernel.org/r/f1787927-b655-4321-b9d9-bc12353c72db@gmx.de/
> Signed-off-by: Rong Zhang <i@rong.moe>
> ---
> 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 f6fef6296251e..f3bc92ac505ac 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
>
Reviewed-by: Derek J. Clark <derekjohn.clark@gmail.com>
Thanks,
Derek