linux-kernel - Re: sky2 PHY setup

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Date:	Sat, 7 Apr 2007 11:53:48 -0600
From:	Rob Sims <lkml-z@...sims.com>
To:	Stephen Hemminger <shemminger@...ux-foundation.org>
Cc:	Thomas Glanzmann <thomas@...nzmann.de>,
	LKML <linux-kernel@...r.kernel.org>,
	Andreas Allgöwer <andreas.allgoewer@....de>,
	Michael Gernoth <simigern@....informatik.uni-erlangen.de>
Subject: Re: sky2 PHY setup

On Wed, Apr 04, 2007 at 11:19:30AM -0700, Stephen Hemminger wrote:
> On Mon, 26 Mar 2007 21:24:06 -0600
> Rob Sims <lkml-z@...sims.com> wrote:
> 
> > On Fri, Mar 16, 2007 at 02:16:48PM -0700, Stephen Hemminger wrote:

> > > Use ethtool -S to if there are any pause frames, etc. See if frames are
> > > still making it into PHY statistics but not being received.
> > > 
> > > Use ethtool -d to dump registers. Need current version of ethtool with decode logic.
> > > 
> > > Then look for things like is Ram buffer read/write pointer changing?
> > > 
> > > Is GMAC stuck in pause:
> > > 
> > > Normal is:
> > > 	GMAC 1
> > > 	Status                       0x5010  (see GM_GPSR_XXX in sky2.h)
> > > 	Control                      0x1800
> > > 
> > > Stuck is
> > > 	GMAC 1
> > > 	Status			     0x5810 (or 0x5A10)
> > 
> > First, here's the described hang in action, on the Core2 Duo on a 1Gb
> > hub:
> > GMAC 1 Status/Control remains at 0x5010/0x1800 until module is removed.
> > Read/write buffer pointers are changing.  Full ethtool output in
> > http://www.robsims.com/sky2.netmon.log.gz
> > 
> > This machine was also having major throughput problems - 17 kB/s.
> > Rebooting brought it to ~ 20 MB/s.  Booting into a kernel with the
> > proprietary sk98lin kernel module showed ~ 80MB/s.  Finally, returning
> > to sky2 gave 117 MB/s.  Tests run using netcat, dd, /dev/zero, and
> > /dev/null, transmitting from the problem box to an e1000 via a Netgear
> > GS108.  No hangs were observed during the "load test."
> 
> The vendor driver does not do hardware flow control correctly. It ignores
> Tx pause frames.
 
> Were you using Jumbo MTU?

No - 1500.

> You might have over run the hub and it wedged.  Try doing:
> 	ethtool -r eth0
> that forces a down/up

I'm still seeing throughput drop to under 1 Mb/s (50-100kB/s)
periodically.  I did an ethtool -S and ethtool -d to capture state.
(sky2-fail.log).  I ran ethtool -r and retested; no change
(sky2-ethtool-r.log).  Finally, ifdown - rmmod - modprobe - ifup, which
restored to Gigabit speeds (96+ MB/s), (sky2-modcycle.log).

Please let me know if there's anything else I can poke into.  As a
reminder, this is a 88E8053 r20.  Next time I see a degradation, I'll
try cycling the switch.
-- 
Rob

View attachment "sky2-fail.log" of type "text/plain" (6405 bytes)

View attachment "sky2-ethtool-r.log" of type "text/plain" (6405 bytes)

View attachment "sky2-modcycle.log" of type "text/plain" (6364 bytes)

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