linux-kernel - Re: [PATCH] i2c: mpc: Use atomic read and fix break condition

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Message-ID: <d9a9d4db-9e21-288d-40d5-0eef198146fb@alliedtelesis.co.nz>
Date:   Thu, 9 Dec 2021 19:47:36 +0000
From:   Chris Packham <Chris.Packham@...iedtelesis.co.nz>
To:     "wsa@...nel.org" <wsa@...nel.org>,
        "mbizon@...ebox.fr" <mbizon@...ebox.fr>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] i2c: mpc: Use atomic read and fix break condition


On 9/12/21 10:21 pm, wsa@...nel.org wrote:
>> we'd hit the 100us timeout in the poll). But I see no evidence of that
>> actually happening (and no idea what arbitration lost means w.r.t i2c).
> On a bus with multiple masters, it means the other master has won the
> arbitration because the address it wants to talk to contains more 0 bits.
>
>> I don't know that there is a maximum clock stretch time (we certainly
>> know there are misbehaving devices that hold SCL low forever). The SMBUS
>> protocol adds some timeouts but as far as I know i2c says nothing about
>> how long a remote device can hold SCL.
> The above is all correct.
>
> Even with the unclear situation about the 100us, I think this should go
> to for-current soon, right?
Please and thank you.