Re: [PATCH V2 0/6] arm_smp_twd: mpcore_wdt: Fix MPCORE watchdog setup

Catalin Marinas
2011-07-06T11:05:52Z

(sorry for reposting - did something wrong with the SMTP configuration
and the original mail was rejected as spam by most recipients)

On Wed, Jul 06, 2011 at 11:14:56AM +0100, Russell King - ARM Linux wrote:
> On Wed, Jul 06, 2011 at 11:05:51AM +0100, Marc Zyngier wrote:
> > On 05/07/11 20:00, Vitaly Kuzmichev wrote:
> > > The series of patches fixes various bugs in ARM MPCORE watchdog setup.
> > > They also introduce some changes in common ARM_SMP_TWD timer setup code.
> > > The PATCH 2/6 adds an exported function to obtain twd timer rate in
> > > mpcore_wdt. However, this solution might be unacceptable, and the
> > > better is to copy calibration loop and clk_get_rate calling to mpcore_wdt.
> >
> > My take on this is that the calibration loop should simply be killed
> > once Colin's patch using the "smp_twd" clock is merged and relevant
> > platforms updated. Once this is done, the watchdog driver should use the
> > clock directly, without exporting a symbol.
>
> Do we know why the calibration was initially introduced? FWIR, it came
> from the SMP group in ARM, so I guess they had a reason for it rather
> than copying x86.

I think it was introduced because the TWD frequency is half of the CPU
frequency but the latter may not be known - boot monitor configuration
could change it.

--
Catalin