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Message-ID: <473048522551f1cae5273eb4cd31b732d6e33e53.camel@codeconstruct.com.au>
Subject: Re: [PATCH] mctp i2c: Requeue the packet when arbitration is lost
From:   Jeremy Kerr <jk@codeconstruct.com.au>
To:     Quan Nguyen <quan@os.amperecomputing.com>,
        Matt Johnston <matt@codeconstruct.com.au>,
        "David S . Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, openbmc@lists.ozlabs.org,
        Open Source Submission <patches@amperecomputing.com>
Cc:     Phong Vo <phong@os.amperecomputing.com>,
        Thang Nguyen <thang@os.amperecomputing.com>,
        Dung Cao <dung@os.amperecomputing.com>
Date:   Thu, 30 Nov 2023 16:03:09 +0800
In-Reply-To: <20231130075247.3078931-1-quan@os.amperecomputing.com>
References: <20231130075247.3078931-1-quan@os.amperecomputing.com>
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Hi Quan,

> If arbitration is lost, __i2c_transfer() returns -EAGAIN and the
> packet should be resent.
>=20
> 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/d=
rivers/i2c/i2c-core-base.c#n2223

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

Cheers,


Jeremy