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. -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
