From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Brownell Subject: Re: [PATCH] OMAP: MMC: recover from transfer failures - Resend Date: Sun, 8 Feb 2009 12:27:03 -0800 Message-ID: <200902081227.03526.david-b@pacbell.net> References: <20081207213617.10456.43951.stgit@localhost> <20090205121045.4022c319.akpm@linux-foundation.org> Reply-To: dbrownell@users.sourceforge.net Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from smtp116.sbc.mail.sp1.yahoo.com ([69.147.64.89]:39645 "HELO smtp116.sbc.mail.sp1.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752791AbZBHU1H (ORCPT ); Sun, 8 Feb 2009 15:27:07 -0500 In-Reply-To: Content-Disposition: inline Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Paul Walmsley Cc: Andrew Morton , Jean Pihet , tony@atomide.com, ext-adrian.hunter@nokia.com, linux-arm-kernel@lists.arm.linux.org.uk, linux-omap@vger.kernel.org, jarkko.lavinen@nokia.com, drzeus-mmc@drzeus.cx, linux-kernel@vger.kernel.org On Thursday 05 February 2009, Paul Walmsley wrote: >=20 > > > +=A0=A0=A0while (OMAP_HSMMC_READ(host->base, > > > + =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0SYSCTL) &= SRD) > > > + =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0; > >=20 > > Is a __raw_readl() sufficient to prevent the cpu from burning up he= re, > > or should we add cpu_relax()? >=20 > The __raw_readl() should be sufficient. =A0The MMC controller is loca= ted on=20 > the L4 CORE interconnect, so the round trip latency for the read from= MMC=20 > is at least 90 ns, while the CPU cycle time is only about 1 to 2 ns. It's still good policy to have a cpu_relax() in such loops. Not that it'll do much on most ARMs, but empty statements are in general worth avoiding. -- To unsubscribe from this list: send the line "unsubscribe linux-omap" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html