From mboxrd@z Thu Jan 1 00:00:00 1970 From: Valdis.Kletnieks@vt.edu Subject: Re: [PATCH 01/16] hpsa: do readl after writel in main i/o path to ensure commands don't get lost. Date: Wed, 04 May 2011 13:54:22 -0400 Message-ID: <11821.1304531662@localhost> 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 Return-path: In-Reply-To: Your message of "Wed, 04 May 2011 11:37:35 MDT." <20110504173735.GB22953@parisc-linux.org> Sender: linux-kernel-owner@vger.kernel.org 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 List-Id: linux-scsi@vger.kernel.org --==_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--