From mboxrd@z Thu Jan 1 00:00:00 1970 From: Grant Likely Subject: Re: [PATCH 03/12] fs_enet: Add FEC TX Alignment workaround for MPC5121. Date: Wed, 6 May 2009 16:42:55 -0600 Message-ID: References: <1241640919-4650-1-git-send-email-wd@denx.de> <1241640919-4650-4-git-send-email-wd@denx.de> <20090506221250.C977183420E8@gemini.denx.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: linuxppc-dev@ozlabs.org, John Rigby , Piotr Ziecik , netdev@vger.kernel.org, John Rigby , Detlev Zundel To: Wolfgang Denk Return-path: Received: from yx-out-2324.google.com ([74.125.44.30]:44615 "EHLO yx-out-2324.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751197AbZEFWnP convert rfc822-to-8bit (ORCPT ); Wed, 6 May 2009 18:43:15 -0400 Received: by yx-out-2324.google.com with SMTP id 3so237672yxj.1 for ; Wed, 06 May 2009 15:43:15 -0700 (PDT) In-Reply-To: <20090506221250.C977183420E8@gemini.denx.de> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, May 6, 2009 at 4:12 PM, Wolfgang Denk wrote: > Dear Grant Likely, > > In message you wrote: >> >> > The FEC on 5121 has problems with misaligned tx buffers. >> > The RM says any alignment is ok but empirical results >> > show that packet buffers ending in 0x1E will sometimes >> > hang the FEC. Other bad alignment does not hang but will >> > cause silent TX failures resulting in about a 1% packet >> > loss as tested by ping -f from a remote host. >> > >> > This patch is a work around that copies every tx packet >> > to an aligned skb before sending. >> >> OUCH! > > Yes :-( > >> > +#else >> > +#define tx_skb_align_workaround(dev, skb) (skb) >> > +#endif >> >> Another use of #ifdef blocks. =A0What is the multiplatform impact? > > Hm... Can you recommend a better way to solve the problem? Suggestion= s > are welcome. I'd rather see a runtime selectable workaround. ie. enable it based on the compatible property. g. --=20 Grant Likely, B.Sc., P.Eng. Secret Lab Technologies Ltd.