Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755120Ab1EDRze (ORCPT ); Wed, 4 May 2011 13:55:34 -0400 Received: from lennier.cc.vt.edu ([198.82.162.213]:55334 "EHLO lennier.cc.vt.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754097Ab1EDRzc (ORCPT ); Wed, 4 May 2011 13:55:32 -0400 X-Mailer: exmh version 2.7.2 01/07/2005 with nmh-1.3-dev To: Matthew Wilcox Cc: scameron@beardog.cce.hp.com, Tomas Henzl , james.bottomley@hansenpartnership.com, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, smcameron@yahoo.com, akpm@linux-foundation.org, mikem@beardog.cce.hp.com Subject: Re: [PATCH 01/16] hpsa: do readl after writel in main i/o path to ensure commands don't get lost. In-Reply-To: Your message of "Wed, 04 May 2011 11:37:35 MDT." <20110504173735.GB22953@parisc-linux.org> From: Valdis.Kletnieks@vt.edu References: <20110503195750.5478.54853.stgit@beardog.cce.hp.com> <20110503195849.5478.13229.stgit@beardog.cce.hp.com> <4DC13566.5070203@redhat.com> <20110504125212.GC5997@beardog.cce.hp.com> <10639.1304530101@localhost> <20110504173735.GB22953@parisc-linux.org> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="==_Exmh_1304531662_7352P"; micalg=pgp-sha1; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit Date: Wed, 04 May 2011 13:54:22 -0400 Message-ID: <11821.1304531662@localhost> X-Mirapoint-Received-SPF: 198.82.161.152 auth3.smtp.vt.edu Valdis.Kletnieks@vt.edu 2 pass X-Mirapoint-IP-Reputation: reputation=neutral-1, source=Fixed, refid=n/a, actions=MAILHURDLE SPF TAG X-Junkmail-Status: score=10/50, host=dagger.cc.vt.edu X-Junkmail-Signature-Raw: score=unknown, refid=str=0001.0A020205.4DC192CF.00CB,ss=1,fgs=0, ip=0.0.0.0, so=2010-07-22 22:03:31, dmn=2009-09-10 00:05:08, mode=single engine X-Junkmail-IWF: false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1177 Lines: 35 --==_Exmh_1304531662_7352P Content-Type: text/plain; charset=us-ascii On Wed, 04 May 2011 11:37:35 MDT, Matthew Wilcox said: > > This probably needs a comment like > > /* don't care - dummy read just to force write posting to chipset */ > > or similar. I'm assuming it's just functioning as a barrier-type flush of some sort? > > It's a PCI write flush. It's not clear to me why it's needed here, > though. The write will eventually get to the device; why we need to > make the CPU wait around for it to actually get there doesn't make sense. Exactly why I think it needs a one-liner comment. :) --==_Exmh_1304531662_7352P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Exmh version 2.5 07/13/2001 iD8DBQFNwZLOcC3lWbTT17ARAoxZAKCC6uTzzQpErmifrHpBnMEda5m7+gCgsmSa hihEfg9c6H21ti8tVTcsssQ= =akVN -----END PGP SIGNATURE----- --==_Exmh_1304531662_7352P-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/