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Date: Tue, 7 Feb 2017 14:14:40 +0100
From: Andrew Lunn <andrew@lunn.ch>
To: David Laight <David.Laight@ACULAB.COM>
Cc: Florian Fainelli <f.fainelli@gmail.com>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "zefir.kurtisi@neratec.com" <zefir.kurtisi@neratec.com>,
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        Philippe Reynes <tremyfr@gmail.com>,
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        Jisheng Zhang <jszhang@marvell.com>, Jarod Wilson <jarod@redhat.com>,
        open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH net-next 4/4] net: dsa: Do not clobber PHY link outside
 of state machine
Message-ID: <20170207131440.GF31560@lunn.ch>
References: <20170206235523.23216-1-f.fainelli@gmail.com>
 <20170206235523.23216-5-f.fainelli@gmail.com>
 <20170207001132.GB30169@lunn.ch>
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> Related is that polling the phy status every second can be bad news for
> system latency.
> Typically it involves bit-bashing an interface with spin-delays to
> meet the slow timings (with extra delays to allow for posted writes).
> An alternative would be to do a very slow bit-bang on each timer tick,
> this would need to be sped up and finished before any other actions.

Or just use PHY interrupts. That completely stops the MDIO polling.

   Andrew