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

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Date:   Tue, 23 Nov 2021 14:41:13 +0900
From:   Hector Martin <marcan@...can.st>
To:     Janne Grunau <j@...nau.net>, Sven Peter <sven@...npeter.dev>,
        Alyssa Rosenzweig <alyssa@...enzweig.io>,
        Rob Herring <robh+dt@...nel.org>
Cc:     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 23/11/2021 07.58, Janne Grunau wrote:
> Apple M1 has at least 5 i2c controllers. i2c0, i2c1 and i2c3 are used
> on all M1 Mac devices. The 2020 Mac Mini uses i2c2 and the 13-inch
> MacBook Pro uses i2c2 and i2c4.

On further testing: i2c3 is not used on the 1GbE variant of j274. iBoot 
actually kills the node entirely. The interesting thing is it doesn't 
work; it times out probe transactions. I suspect iBoot does not enable 
its clock or something like that.

I'll poke around this on IRC, but a priori we probably need m1n1 code to 
kill this node when the ADT doesn't have it. Maybe I should generalize 
the dwc3 killing code...

-- 
Hector Martin (marcan@...can.st)
Public Key: https://mrcn.st/pub