Messages in this thread | | | From | David Brownell <> | Subject | Re: [PATCH] OMAP: MMC: recover from transfer failures - Resend | Date | Sun, 8 Feb 2009 12:27:03 -0800 |
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On Thursday 05 February 2009, Paul Walmsley 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.
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.
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