linux-kernel - Re: [PATCH v2 1/4] power: supply: add support for max77759 fuel gauge

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <CADrjBPpkiNvxGjw_iLG3tw2MNy62trao+igaMMX_zjL44+w1EQ@mail.gmail.com>
Date: Wed, 8 Jan 2025 09:49:13 +0000
From: Peter Griffin <peter.griffin@...aro.org>
To: t.antoine@...ouvain.be
Cc: Sebastian Reichel <sre@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Dimitri Fedrau <dima.fedrau@...il.com>, Catalin Marinas <catalin.marinas@....com>, 
	Will Deacon <will@...nel.org>, Alim Akhtar <alim.akhtar@...sung.com>, 
	André Draszik <andre.draszik@...aro.org>, 
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	linux-samsung-soc@...r.kernel.org
Subject: Re: [PATCH v2 1/4] power: supply: add support for max77759 fuel gauge

Hi Thomas,

On Thu, 2 Jan 2025 at 11:16, Thomas Antoine via B4 Relay
<devnull+t.antoine.uclouvain.be@...nel.org> wrote:
>
> From: Thomas Antoine <t.antoine@...ouvain.be>
>
> The interface of the Maxim max77759 fuel gauge has a lot of common with the
> Maxim max1720x. The major difference is the lack of non-volatile memory
> slave address. No slave is available at address 0xb of the i2c bus, which
> is coherent with the following driver from google: line 5836 disables
> non-volatile memory for m5 gauge.
>
> Link: https://android.googlesource.com/kernel/google-modules/bms/+/1a68c36bef474573cc8629cc1d121eb6a81ab68c/max1720x_battery.c
>
> Other differences include the lack of V_BATT register to read the battery
> level and a difference in the way to identify the chip (the same register
> is used but not the same mask).
>
> Add support for the max77759 by allowing to use the non-volatile
> memory or not based on the chip. Also add the V_CELL regsister as a
> fallback to read voltage value in the case where read of V_BATT fails.
>
> The cast is necessary to avoid an overflow when the value of the register
> is above 54975 (equivalent to a voltage around 4.29 V).
>
> The regmap of the max77759 will lead the read to fail for V_BATT and to
> correctly use V_CELL instead. This regmap was proposed by André Draszik in
>
> Link: https://lore.kernel.org/all/d1bade77b5281c1de6b2ddcb4dbbd033e455a116.camel@linaro.org/

Firstly thanks for working on this :) Fuel gauge is a great addition
to the Pixel 6 upstream support.

It would be good if you can document what you consider "working" with
this series applied. I think it's fine for support to come
incrementally (say feature additions to the driver to support x,y,z).
But anything that is now reported in sysfs with this series applied
should be accurate (or alternatively not exposed for MAX77759 variant
if it's not accurate and it's unclear from checking the downstream
driver how to fix it).

Thanks,

Peter