Subject: Re: MPC5200B, many FEC_IEVENT_RFIFO_ERRORs until link down

From: Wolfgang Grandegger <[email-masked]>
Date: Tue, 30 Mar 2010 12:46:12 +0200

Roman Fietze wrote:
> Hello,
> 
> I think this is a never ending story. This error still happens under
> higher load every few seconds, until I get a "PHY: f0003000:00 - Link
> is Down", on my box easiliy reproducable after maybe 15 to 30 seconds.
> I can recover using "ip link set down/up dev eth0".
> 
> I double checked that I'm using the most recent version of this driver
> (checked with DENX, benh master/next, using Wolfgang Denk's version of
> the 2.6.33), this includes the locking patches from Asier Llano, the
> hard setting of mii_speed in the PHY mdio transfer routine of course.
> I tried all 8 combinations of PLDIS, BSDIS and SE, with and without
> CONFIG_NOT_COHERENT_CACHE.
> 
> As some of you probably remember, I'm running this controller under
> high load on FEC, ATA and LPC. As soon as "the" load is going above a
> certain level I get those FEC RFIFO errors, sometimes ATA errors
> (MWDMA2) and sometimes even lost SDMA interrupts using BestComm with
> the SCLPC (now switched back to simple PIO). I quite sure almost all
> of this is the BestComm's fault.

This problem shows up quickly with NAPI, but I have never observed it
with the current version. The error occurs when the software is not able
to readout the messages in time. Unfortunately, dealing with Bestcomm is
a pain.

> Did somebody already try the latest NAPI patches, which might give me
> a slight chance to have a workaround? Any idea or upcoming patch to
> address this problem once more, and if it's just by recovering e.g.
> within mpc52xx_fec_mdio_transfer's timeout using some other dirty
> workaround?

Yes, I have a NAPI version ready for testing. I will roll it out as RFC
today or tomorrow.

Wolfgang.