linux-kernel - Re: [PATCH v2 1/2] i2c: ocores: increase poll timeout to total transfer timeout

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Message-ID: <aWdjQ1mubxk3m0JY@ninjato>
Date: Wed, 14 Jan 2026 10:34:59 +0100
From: Wolfram Sang <wsa+renesas@...g-engineering.com>
To: Matthias Schiffer <matthias.schiffer@...tq-group.com>
Cc: Andrew Lunn <andrew@...n.ch>, Peter Korsgaard <peter@...sgaard.com>,
	Andi Shyti <andi.shyti@...nel.org>, linux-i2c@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux@...tq-group.com
Subject: Re: [PATCH v2 1/2] i2c: ocores: increase poll timeout to total
 transfer timeout

Hi Matthias,

> This code does not have interrupts disabled, we could not fall back from
> read_poll_timeout_atomic() to read_poll_timeout() otherwise.

Yes, that's what I thought as well.

> that a sleeping wait would make it more likely for a switch to a different task
> to happen after every byte, negatively impacting I2C performance; this is not
> something I have verified however.

Quite some prominent controller drivers use readX_poll_timeout(), so it
really seems there is no huge penalty in practice. Especially not with
cores so fast these days that tasks can be served even in 100us.

> It is spinning for 1ms because that's what the old code did (which only spun
> without fallback to sleeping).

I understand. Yet, I think the spinning is legacy behaviour and I would
prefer plain readX_poll_timeout(). Unless there is something I
overlooked. Makes the code simpler and easier to maintain.

Thanks and happy hacking,

   Wolfram

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