Re: [PATCH] ACPI / PMIC: xpower: Fix TS-pin current-source handling

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Hi,

On 07-01-19 11:59, Rafael J. Wysocki wrote:
On Fri, Jan 4, 2019 at 11:11 PM Hans de Goede <hdegoede@xxxxxxxxxx> wrote:

The current-source used for the battery temp-sensor (TS) is shared with the
GPADC. For proper fuel-gauge and charger operation the TS current-source
needs to be permanently on. But to read the GPADC we need to temporary
switch the TS current-source to ondemand, so that the GPADC can use it,
otherwise we will always read an all 0 value.

The switching from on to on-ondemand is not necessary when the TS
current-source is off (this happens on devices which do not have a TS).

Prior to this commit there were 2 issues with our handling of the TS
current-source switching:

1) We were writing hardcoded values to the ADC TS pin-ctrl register,
overwriting various other unrelated bits. Specifically we were overwriting
the current-source setting for the TS and GPIO0 pins, forcing it to 80ųA
independent of its original setting. On a Chuwi Vi10 tablet this was
causing us to get a too high adc value (due to a too high current-source)
resulting in acpi_lpat_raw_to_temp() returning -ENOENT, resulting in:

ACPI Error: AE_ERROR, Returned by Handler for [UserDefinedRegion]
ACPI Error: Method parse/execution failed \_SB.SXP1._TMP, AE_ERROR

This commit fixes this by using regmap_update_bits to change only the
relevant bits.

2) At the end of intel_xpower_pmic_get_raw_temp() we were unconditionally
enabling the TS current-source even on devices where the TS-pin is not used
and the current-source thus was off on entry of the function.

This commit fixes this by checking if the TS current-source is off when
entering intel_xpower_pmic_get_raw_temp() and if so it is left as is.

Fixes: 58eefe2f3f53 ("ACPI / PMIC: xpower: Do pinswitch ... reading GPADC")

AFAICS this commit went in during the 4.14 cycle, so I'm assuming the
patch to be stable-candidate material, right?

Right.

Regards,

Hans





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