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Message-ID: <852eaa7b5040124049e51ceba2d13a5799cb6748.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 17:40:51 +0800
In-Reply-To: <706506b7-a89c-4dfc-b233-be7822eb056e@os.amperecomputing.com>
References: <20231130075247.3078931-1-quan@os.amperecomputing.com>
         <473048522551f1cae5273eb4cd31b732d6e33e53.camel@codeconstruct.com.au>
         <706506b7-a89c-4dfc-b233-be7822eb056e@os.amperecomputing.com>
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Hi Quan,

> With this commit, we all see the packets go through peacefully just
> by requeueing the packets at MCTP layer and eliminated the need to
> retry in PLDM layer which would need more time.

It's certainly possible that this tries harder to send MCTP packets,
but it's just duplicating the retry mechanism already present in the
i2c core.

Why do we need another retry mechanism here? How is the i2c core retry
mechanism not sufficient?

It would seem that you can get the same behaviour by adjusting the
retries/timeout limits in the core code, which has the advantage of
applying to all arbitration loss events on the i2c bus, not just for
MCTP tx.

Cheers,


Jeremy