Re: [PATCH] platform/x86: hp-wmi: Use only the low byte of the thermal profile

["Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>]

On Sun, 25 Oct 2026, Akhil Boyapati wrote:

> On the HP Spectre x360 14 (board 8C15) the firmware answers the
> thermal profile query (0x4C, read) with more than the profile: the
> DSDT's GTPS method returns the profile in byte 0, OEM flags in byte 1
> and the device posture in byte 2. In Quiet mode in laptop posture the
> value is 0x00041103.
> 
> thermal_profile_get() returns the whole value, so
> hp_wmi_platform_profile_get() matches no profile and reading
> /sys/firmware/acpi/platform_profile fails with -EINVAL. This also
> breaks power-profiles-daemon and tuned-ppd. Probe writes the
> unmasked value back, which only works because the firmware's write
> method (STPS) uses byte 0.
> 
> Mask the value to its low byte. Boards that return only the profile
> are unaffected.
> 
> Tested on board 8C15 (kernel 7.2.11, module built from this tree's
> driver with the change applied): platform_profile reads back correctly
> after setting each of cool, quiet, balanced and performance, and the
> firmware's ODVP0 follows (3, 4, 2, 1). Not tested on other boards.
> 
> Fixes: 4296f679ca50 ("platform/x86: hp-wmi: add platform profile support")
> Assisted-by: LLM
> Signed-off-by: Akhil Boyapati <boyakhil978@gmail.com>
> ---
>  drivers/platform/x86/hp/hp-wmi.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/platform/x86/hp/hp-wmi.c b/drivers/platform/x86/hp/hp-wmi.c
> index 52077833a..6180f1d21 100644
> --- a/drivers/platform/x86/hp/hp-wmi.c
> +++ b/drivers/platform/x86/hp/hp-wmi.c
> @@ -2117,7 +2117,13 @@ static int platform_profile_omen_set(struct device *dev,
>  
>  static int thermal_profile_get(void)
>  {
> -	return hp_wmi_read_int(HPWMI_THERMAL_PROFILE_QUERY);
> +	int tp = hp_wmi_read_int(HPWMI_THERMAL_PROFILE_QUERY);
> +
> +	/*
> +	 * Only the low byte is the thermal profile. Some firmware (e.g. board
> +	 * 8C15) packs OEM flags and the device posture into the upper bytes.
> +	 */
> +	return tp < 0 ? tp : tp & 0xff;

Add a named define and use FIELD_GET(). Then the comment doesn't seem even 
required.

Please keep call and it's error handling next to each other (convert 
this to the usual error handling pattern with if). Because of that you 
cannot make the call in variable declaration block but that's fine.

-- 
 i.