linux-kernel - Re: [PATCH v3 3/4] arm64: dts: apple: t8103: Add i2c nodes

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

Date:   Thu, 25 Nov 2021 16:50:28 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Hector Martin <marcan@...can.st>
Cc:     Janne Grunau <j@...nau.net>, Sven Peter <sven@...npeter.dev>,
        Alyssa Rosenzweig <alyssa@...enzweig.io>,
        Rob Herring <robh+dt@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/4] arm64: dts: apple: t8103: Add i2c nodes

On Wed, Nov 24, 2021 at 6:42 AM Hector Martin <marcan@...can.st> wrote:

> Pulling down an I2C bus between transactions is not legal; the idle
> state has to be high.

Oh right.

> Apple are actually not very good at configuring GPIOs for power saving;
> e.g. the I/Os for that unused i2c bus still have their input buffers
> turned on, which is a waste of power. If they wanted to save the
> smallest drop of power they'd turn that off. But the effect of this is
> so trivial it probably makes no difference in the context of a laptop,
> nevermind a desktop like the Mac Mini.

Hm that's true. The saying is that 99% is the backlight, the remaining 1% isn't
so significant after that.

Yours,
Linus Walleij