Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754795Ab1EDR3f (ORCPT ); Wed, 4 May 2011 13:29:35 -0400 Received: from lennier.cc.vt.edu ([198.82.162.213]:32943 "EHLO lennier.cc.vt.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751524Ab1EDR3e (ORCPT ); Wed, 4 May 2011 13:29:34 -0400 X-Mailer: exmh version 2.7.2 01/07/2005 with nmh-1.3-dev To: scameron@beardog.cce.hp.com Cc: 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 07:52:12 CDT." <20110504125212.GC5997@beardog.cce.hp.com> 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> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="==_Exmh_1304530101_7352P"; micalg=pgp-sha1; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit Date: Wed, 04 May 2011 13:28:21 -0400 Message-ID: <10639.1304530101@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=zidane.cc.vt.edu X-Junkmail-Signature-Raw: score=unknown, refid=str=0001.0A020205.4DC18CB8.015F,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: 1635 Lines: 44 --==_Exmh_1304530101_7352P Content-Type: text/plain; charset=us-ascii On Wed, 04 May 2011 07:52:12 CDT, scameron@beardog.cce.hp.com said: > On Wed, May 04, 2011 at 01:15:50PM +0200, Tomas Henzl wrote: > > On 05/03/2011 09:58 PM, Stephen M. Cameron wrote: > > > From: Stephen M. Cameron > > > dev_dbg(&h->pdev->dev, "Sending %x, tag = %x\n", c->busaddr, > > > c->Header.Tag.lower); > > > writel(c->busaddr, h->vaddr + SA5_REQUEST_PORT_OFFSET); > > > + (void) readl(h->vaddr + SA5_REQUEST_PORT_OFFSET); > I just put it there to make it clear that it ignoring the return of readl is > done intentionally, not accidentally. If this goes against some coding convention, > whatever, I'm not super attached to the (void), but I did put it there on purpose, > and would have done it in cciss as well, had I thought of it at the time. 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? --==_Exmh_1304530101_7352P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Exmh version 2.5 07/13/2001 iD8DBQFNwYy1cC3lWbTT17ARAtBTAJ99nLBal+gVKChT+db9zUyukiTruQCePk/d zfMU7pRV2aHY12MlQIiuoL8= =qqQi -----END PGP SIGNATURE----- --==_Exmh_1304530101_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/