[U-Boot] [PATCH] Fix bootdelay timeout calculation when SYS_HZ!=1000

[Tom Rini]

On Thu, Mar 21, 2013 at 01:07:18PM -0500, Jon Hunter wrote:
> 
> On 03/21/2013 10:28 AM, Tom Rini wrote:
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> > 
> > On 03/21/2013 11:25 AM, Jon Hunter wrote:
> >>
> >> On 03/21/2013 09:41 AM, Tom Rini wrote:
> >>> On Thu, Mar 21, 2013 at 03:35:40PM +0100, Wolfgang Denk wrote:
> >>>> Dear Tom,
> >>>>
> >>>> In message <514B1036.3090400 at ti.com> you wrote:
> >>>>>
> >>>>>> A system with CONFIG_SYS_HZ != 1000 is _broken_.
> >>>>>
> >>>>> So, RPi is going higher, and Jon hit this on I suspect
> >>>>> omap2420h4 which is also higher (after mathing that all out).
> >>>>> If we no longer support CONFIG_SYS_HZ != 1000 we need to make
> >>>>> that clear (and explain why).
> >>>>
> >>>> It has never been supported, so this is not a case of "no
> >>>> longer". There are several longish threads (about the timer
> >>>> code, especially on ARM) in the archives.
> >>>
> >>> OK, then we need to do something about these platforms today.
> >>> I'm guessing RPi can just be tuned down to 1000 but for
> >>> omap2420h4 it's an interesting value and I don't know about the
> >>> platform well enough to say what we'd need to do to adapt it.
> >>> Jon?
> >>
> >> For OMAP2420, we have a choice of using either a 12MHz or 32kHz
> >> clock to drive the timer. With the 32kHz clock we can get close to
> >> 1000Hz tick but we cannot get it dead on. That's why OMAP has been
> >> using 128Hz tick in the kernel as opposed to 100Hz tick in the
> >> kernel for years (although that was changed recently).
> > 
> > The rest of the OMAP/related platforsm in U-Boot accept that as "good"
> > enough I guess since they've been setting to 1000 for a while / since
> > they went in (depending on the platform in particular).  So if you
> > have time to whack 2420 over and give it some quick testing I'd
> > appreciate it.  Thanks!
> 
> Looks like the OMAP timers are running faster than 1000Hz but the timer
> tick rate is being normalised to 1000Hz by dividing the actual timer
> rate by SYS_HZ. I see ...
> 
> 	readl(&timer_base->tcrr) / (TIMER_CLOCK / CONFIG_SYS_HZ);
> 
> We could do the same for OMAP2420. In fact we could move
> arch/arm/cpu/armv7/omap-common/timer.c to arch/arm/omap-common/timer.c
> and use this for OMAP2420. The legacy OMAP2420 code is very similar to this.

Sounds good to me, thanks!

-- 
Tom
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