linux-kernel - Re: [PATCH] mctp i2c: Requeue the packet when arbitration is lost

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Message-ID: <473048522551f1cae5273eb4cd31b732d6e33e53.camel@codeconstruct.com.au>
Date:   Thu, 30 Nov 2023 16:03:09 +0800
From:   Jeremy Kerr <jk@...econstruct.com.au>
To:     Quan Nguyen <quan@...amperecomputing.com>,
        Matt Johnston <matt@...econstruct.com.au>,
        "David S . Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, openbmc@...ts.ozlabs.org,
        Open Source Submission <patches@...erecomputing.com>
Cc:     Phong Vo <phong@...amperecomputing.com>,
        Thang Nguyen <thang@...amperecomputing.com>,
        Dung Cao <dung@...amperecomputing.com>
Subject: Re: [PATCH] mctp i2c: Requeue the packet when arbitration is lost

Hi Quan,

> If arbitration is lost, __i2c_transfer() returns -EAGAIN and the
> packet should be resent.
> 
> Requeue the packet and increase collisions count on this case.

Are you sure you want to re-queue the packet here? The i2c core would
have already retried on arbitration loss:

  https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/i2c/i2c-core-base.c#n2223

With this change, we would be disregarding the limits in adap->retries
and/or adap->timeout.

Cheers,


Jeremy