netdev - Re: [PATCH 1/2] net: dp83822: disable false carrier interrupt

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Date:   Thu, 23 Jun 2022 14:42:54 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Enguerrand de Ribaucourt 
        <enguerrand.de-ribaucourt@...oirfairelinux.com>
Cc:     davem@...emloft.net, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux@...linux.org.uk,
        hkallweit1@...il.com
Subject: Re: [PATCH 1/2] net: dp83822: disable false carrier interrupt

On Thu, Jun 23, 2022 at 10:51:25AM +0200, Enguerrand de Ribaucourt wrote:
> When unplugging an Ethernet cable, false carrier events were produced by
> the PHY at a very high rate. Once the false carrier counter full, an
> interrupt was triggered every few clock cycles until the cable was
> replugged. This resulted in approximately 10k/s interrupts.
> 
> Since the false carrier counter (FCSCR) is never used, we can safely
> disable this interrupt.
> 
> In addition to improving performance, this also solved MDIO read
> timeouts I was randomly encountering with an i.MX8 fec MAC because of
> the interrupt flood. The interrupt count and MDIO timeout fix were
> tested on a v5.4.110 kernel.

Since this is version 2, you should add v2 into the subject line. See
the submitting patches document in the kernel documentation.

Also, with patch sets, please include a patch 0/X which describes the
big picture.

This is also a bug fix, you are stopping an interrupt storm. So please
include a Fixes: tag indicating where the issue was introduced.

The code itself looks good, it is just getting the processes right.

	Andrew