linux-kernel - Re: [PATCH v3 1/2] net: dp83822: disable false carrier interrupt

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Message-ID: <YrSwgKpa+KUxIZd5@lunn.ch>
Date:   Thu, 23 Jun 2022 20:27:12 +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 v3 1/2] net: dp83822: disable false carrier interrupt

On Thu, Jun 23, 2022 at 03:46:44PM +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.
> 
> Signed-off-by: Enguerrand de Ribaucourt <enguerrand.de-ribaucourt@...oirfairelinux.com>
> Reviewed-by: Andrew Lunn <andrew@...n.ch>
> Fixes: 87461f7a58ab ("net: phy: DP83822 initial driver submission")

For future reference, you should put these in the opposite order. Your
Signed-off-by should come last. Fixes generally comes first.

No need to resend for this patchset.

   Andrew