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Date:   Fri, 12 Jun 2020 12:30:31 +0100
From:   Russell King - ARM Linux admin <linux@armlinux.org.uk>
To:     Sascha Hauer <s.hauer@pengutronix.de>
Cc:     linux-arm-kernel@lists.infradead.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
        kernel@pengutronix.de
Subject: Re: [PATCH v2] net: mvneta: Fix Serdes configuration for 2.5Gbps
 modes
Message-ID: <20200612113031.GI1551@shell.armlinux.org.uk>
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On Fri, Jun 12, 2020 at 12:22:13PM +0100, Russell King - ARM Linux admin wrote:
> On Fri, Jun 12, 2020 at 11:42:08AM +0100, Russell King - ARM Linux admin wrote:
> > With the obvious mistakes fixed (extraneous 'i' and lack of default
> > case), it seems to still work on Armada 388 Clearfog Pro with 2.5G
> > modules.
> 
> ... and the other bug fixed - mvneta_comphy_init() needs to be passed
> the interface mode.

Unrelated to the patch, has anyone noticed that mvneta's performance
seems to have reduced?  I've only just noticed it (which makes 2.5Gbps
rather pointless).  This is iperf between two clearfogs with a 2.5G
fibre link:

root@clearfog21:~# iperf -V -c fe80::250:43ff:fe02:303%eno2
------------------------------------------------------------
Client connecting to fe80::250:43ff:fe02:303%eno2, TCP port 5001
TCP window size: 43.8 KByte (default)
------------------------------------------------------------
[  3] local fe80::250:43ff:fe21:203 port 48928 connected with fe80::250:43ff:fe02:303 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec   553 MBytes   464 Mbits/sec

I checked with Jon Nettleton, and he confirms my recollection that
mvneta on Armada 388 used to be able to fill a 2.5Gbps link.

If Armada 388 can't manage, then I suspect Armada XP will have worse
performance being an earlier revision SoC.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!