Re: [PATCH 3/3] ACPI: PMIC: xpower: Fix _TMP ACPI errors

[Andy Shevchenko <andriy.shevchenko@intel.com>]

On Fri, Nov 26, 2021 at 04:21:09PM +0100, Hans de Goede wrote:
> On some devices with a X-Powers AXP288 PMIC the LPAT tables in the ACPI
> node for the AXP288 PMIC for some reason only describe a small temperature
> range, e.g. 27° - 37° Celcius (assuming the entries are in millidegrees).
> 
> When the tablet is idle in a room at 21° degrees this is causing values
> outside the LPAT table to be read, causing e.g. the following 2 errors
> to get spammed to the logs every 4 seconds! :
> 
> [ 7512.791316] ACPI Error: AE_ERROR, Returned by Handler for [UserDefinedRegion] (20210930/evregion-281)
> [ 7512.791611] ACPI Error: Aborting method \_SB.SXP1._TMP due to previous error (AE_ERROR) (20210930/psparse-529)
> 
> Fix this by clamping the raw value to the LPAT table range before
> passing it to acpi_lpat_raw_to_temp().
> 
> Note clamping has been chosen rather then extrapolating because it is
> unknown how other parts of the ACPI tables will respond to temperature
> values outside of the LPAT range.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>

One nit-pick below.

> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
>  drivers/acpi/pmic/intel_pmic_xpower.c | 23 ++++++++++++++++++++++-
>  1 file changed, 22 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/pmic/intel_pmic_xpower.c b/drivers/acpi/pmic/intel_pmic_xpower.c
> index e844bc1f3df5..61bbe4c24d87 100644
> --- a/drivers/acpi/pmic/intel_pmic_xpower.c
> +++ b/drivers/acpi/pmic/intel_pmic_xpower.c
> @@ -293,12 +293,33 @@ static int intel_xpower_exec_mipi_pmic_seq_element(struct regmap *regmap,
>  	return ret;
>  }
>  
> +static int intel_xpower_lpat_raw_to_temp(struct acpi_lpat_conversion_table *lpat_table,
> +					 int raw)
> +{
> +	struct acpi_lpat first = lpat_table->lpat[0];
> +	struct acpi_lpat last = lpat_table->lpat[lpat_table->lpat_count - 1];
> +
> +	/*
> +	 * Some LPAT tables in the ACPI Device for the AXP288 PMIC for some
> +	 * reason only describe a small temperature range, e.g. 27° - 37°
> +	 * Celcius. Resulting in errors when the tablet is idle in a cool room.
> +	 *
> +	 * To avoid these errors clamp the raw value to be inside the LPAT.
> +	 */

> +	if (first.raw < last.raw)

Wondering what that would mean if this condition is false.

> +		raw = clamp(raw, first.raw, last.raw);
> +	else
> +		raw = clamp(raw, last.raw, first.raw);

clamp_value() slightly better due to type checking.

> +
> +	return acpi_lpat_raw_to_temp(lpat_table, raw);
> +}
> +
>  static const struct intel_pmic_opregion_data intel_xpower_pmic_opregion_data = {
>  	.get_power = intel_xpower_pmic_get_power,
>  	.update_power = intel_xpower_pmic_update_power,
>  	.get_raw_temp = intel_xpower_pmic_get_raw_temp,
>  	.exec_mipi_pmic_seq_element = intel_xpower_exec_mipi_pmic_seq_element,
> -	.lpat_raw_to_temp = acpi_lpat_raw_to_temp,
> +	.lpat_raw_to_temp = intel_xpower_lpat_raw_to_temp,
>  	.power_table = power_table,
>  	.power_table_count = ARRAY_SIZE(power_table),
>  	.thermal_table = thermal_table,
> -- 
> 2.33.1
> 

-- 
With Best Regards,
Andy Shevchenko