linux-kernel - Re: [PATCH v2 5/8] power: supply: qcom_battmgr: Add charge control support

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Message-ID: <219a46d0-446c-4eed-8809-4f2400de0ef9@oss.qualcomm.com>
Date: Sat, 7 Jun 2025 11:46:10 +0200
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
        Fenglin Wu <fenglin.wu@....qualcomm.com>
Cc: György Kurucz <me@...uczgy.com>,
        Sebastian Reichel <sre@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley
 <conor+dt@...nel.org>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Subbaraman Narayanamurthy <subbaraman.narayanamurthy@....qualcomm.com>,
        David Collins <david.collins@....qualcomm.com>,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, kernel@....qualcomm.com,
        devicetree@...r.kernel.org, linux-usb@...r.kernel.org
Subject: Re: [PATCH v2 5/8] power: supply: qcom_battmgr: Add charge control
 support

On 6/3/25 12:37 PM, Dmitry Baryshkov wrote:
> On Tue, Jun 03, 2025 at 01:48:11PM +0800, Fenglin Wu wrote:
>>
>> On 5/31/2025 6:36 PM, György Kurucz wrote:
>>>> Add charge control support for SM8550 and X1E80100.
>>>
>>> Thank you for this, tested on my Lenovo Yoga Slim 7x, the limiting works
>>> well, I finally don't have to worry about leaving my laptop plugged in
>>> for too long.
>>>
>>> One small thing I noticed is that after setting the sysfs values and
>>> rebooting, they report 0 again. The limiting appears to stay in effect
>>> though, so it seems that the firmware does keep the values, but Linux
>>> does not read them back. Indeed, looking at the code, it seems that
>>> actually reading back the values is only implemented for the SM8550.
>>
>> Right.
>>
>> Based on offline information, X1E80100 doesn't support reading back those
>> threshold values in battery management firmware, so I can only use the
>> cached values for sysfs read.
> 
> Which limits usablity of the attribute, it is now impossible to identify
> whether it is enabled or disabled. Is there a chance of fixing that for
> the X1E80100 platform?

Is there a chance we store that value in SDAM and can read it back?

Konrad