From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH net-next-2.6 06/17] sfc: Fix event based MCDI completion and MC REBOOT/CMDDONE ordering issue Date: Fri, 03 Dec 2010 09:09:04 -0800 (PST) Message-ID: <20101203.090904.112597272.davem@davemloft.net> References: <1291333490.3259.23.camel@bwh-desktop> <1291333615.3259.29.camel@bwh-desktop> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, linux-net-drivers@solarflare.com To: bhutchings@solarflare.com Return-path: Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:42671 "EHLO sunset.davemloft.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752393Ab0LCRIh (ORCPT ); Fri, 3 Dec 2010 12:08:37 -0500 In-Reply-To: <1291333615.3259.29.camel@bwh-desktop> Sender: netdev-owner@vger.kernel.org List-ID: From: Ben Hutchings Date: Thu, 02 Dec 2010 23:46:55 +0000 > From: Steve Hodgson > > The mcfw *never* sends CMDDONE when rebooting. Changing this so that it always > sends CMDDONE *before* REBOOT is easy on Siena, but it's not obvious that we > could guarantee to be able to implement this on future hardware. > > Given this, I'm less convinced that the protocol should be changed. > > To reiterate the failure mode: The driver sees this: > > issue command > receive REBOOT event > > Was that reboot event sent before the command was issued, or in > response to the command? If the former then there will be a subsequent > CMDDONE event, if the latter, then there will be no CMDDONE event. > > Options to resolve this are: > > 1. REBOOT always completes an outstanding mcdi request, and we set > the credits count to ignore a subsequent CMDDONE event with > mismatching seqno. > > 2. REBOOT never completes an outstanding mcdi request. If there is > no CMDDONE event then we rely on the mcdi timeout code to complete > the outstanding request, incurring a 10s delay. > > I'd argue that (2) is tidier, but that incurring a 10s delay is a little > needless. Let's go with (1). > > Signed-off-by: Ben Hutchings Applied.