From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jean Pihet Subject: Re: [PATCH] OMAP: MMC: recover from transfer failures - Resend Date: Fri, 6 Feb 2009 14:22:32 +0100 Message-ID: <200902061422.32689.jpihet@mvista.com> References: <20081207213617.10456.43951.stgit@localhost> <20090205121045.4022c319.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from gateway-1237.mvista.com ([63.81.120.158]:49784 "EHLO gateway-1237.mvista.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753141AbZBFNXA (ORCPT ); Fri, 6 Feb 2009 08:23:00 -0500 In-Reply-To: Content-Disposition: inline Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Paul Walmsley , Andrew Morton Cc: 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 21:32:03 Paul Walmsley wrote: > On Thu, 5 Feb 2009, Andrew Morton wrote: > > On Tue, 3 Feb 2009 15:05:58 +0100 > > > > Jean Pihet wrote: > > > + while (OMAP_HSMMC_READ(host->base, > > > + SYSCTL) & SRD) > > > + ; > > > > Is a __raw_readl() sufficient to prevent the cpu from burning up here, > > or should we add cpu_relax()? > > The __raw_readl() should be sufficient. The MMC controller is located on > the L4 CORE interconnect, so the round trip latency for the read from MMC > is at least 90 ns, while the CPU cycle time is only about 1 to 2 ns. Ok. > > > An infinite loop which assumes the hardware is perfect is always a > > worry. But I see the driver already does that, so we're no worse off.. Do you want a finite loop with udelay in it? I located 4 places were this could be used. If so I can generate a new patch for that. > > - Paul Regards, Jean