linux-kernel - Re: [PATCH v5 9/9] power: supply: qcom_battmgr: handle charging state change notifications

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Message-ID: <d9db8b82-9000-478b-a7b5-93792f1e1bea@oss.qualcomm.com>
Date: Thu, 18 Sep 2025 10:01:24 +0800
From: Fenglin Wu <fenglin.wu@....qualcomm.com>
To: Konrad Dybcio <konrad.dybcio@....qualcomm.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>,
        Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
        Bryan O'Donoghue <bryan.odonoghue@...aro.org>
Cc: Subbaraman Narayanamurthy <subbaraman.narayanamurthy@....qualcomm.com>,
        David Collins <david.collins@....qualcomm.com>,
        György Kurucz <me@...uczgy.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 v5 9/9] power: supply: qcom_battmgr: handle charging state
 change notifications


On 9/17/2025 7:14 PM, Konrad Dybcio wrote:
> On 9/17/25 12:15 PM, Fenglin Wu via B4 Relay wrote:
>> From: Fenglin Wu <fenglin.wu@....qualcomm.com>
>>
>> The X1E80100 battery management firmware sends a notification with
>> code 0x83 when the battery charging state changes, such as switching
>> between fast charge, taper charge, end of charge, or any other error
>> charging states. The same notification code is used with bit[16] set
>> if charging stops due to reaching the charge control end threshold.
>> Additionally, a 2-bit value is added in bit[18:17] with the same code
>> and used to indicate the charging source capability: a value of 2
>> represents a strong charger, 1 is a weak charger, and 0 is no charging
>> source. The 3-MSB [18:16] in the notification code is not much useful
>> for now, hence just ignore them and trigger a power supply change event
>> whenever 0x83 notification code is received. This helps to eliminate the
>> unknown notification error messages.
> Thank you for explaining the technical background.
>
> Please hit enter somewhere in your commit message, this is a very
> long paragraph, making it difficult to read.
I just realized I made a mistake on the bit position, it should be 
bit[8] for reaching to the charge control threshold, bit[10:9] for 
charging source capability. I don't know what I was thinking when 
writing the commit text :(. I will correct them in the next patch.
>
> I believe this maps to:
>
> 0 -> POWER_SUPPLY_CHARGE_TYPE_NONE
> 1 -> POWER_SUPPLY_CHARGE_TYPE_TRICKLE
> 2 -> POWER_SUPPLY_CHARGE_TYPE_FAST (or _STANDARD, I see battmgr code
> reports them both as 2)
>
> However, we already set it to none/trickle/standard(taper) based on
> the usual notifications, so I'm not sure if these are more common or
> arrive outside the normal state changes - if so, perhaps we can take
> them into account as well?

This is not related with the real charging status. I double checked in 
the battery management firmware, it is checking the charging source 
power capability by multiplying maximum voltage and current reading from 
the PDOs. Any charger adapter with a maximum power below 60W is 
identified as a slow/weak charger.

>
> I think it also warrants a:
>
> Reported-by: Sebastian Reichel <sebastian.reichel@...labora.com>
ACK
> Konrad