Re: [PATCH] OMAP: MMC: recover from transfer failures - Resend

Jean Pihet
2009-02-06T13:23:17Z

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 <jpihet@mvista.com> 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