On Wed, May 15, 2013 at 03:16:52PM +0200, Arnd Bergmann wrote:
> > +static void moxart_idle(void)
> > +{
> > + /*
> > + * Because of broken hardware we have to enable interrupts or the CPU
> > + * will never wakeup... Acctualy it is not very good to enable
> > + * interrupts first since scheduler can miss a tick, but there is
> > + * no other way around this. Platforms that needs it for power saving
> > + * should call enable_hlt() in init code, since by default it is
> > + * disabled.
> > + */
> > +/* local_irq_enable();
> > + cpu_do_idle();*/
> > +}
> > +
> > +static int __init moxart_idle_init(void)
> > +{
> > + arm_pm_idle = moxart_idle;
> > + return 0;
> > +}
> > +
> > +arch_initcall(moxart_idle_init);
>
> This does not seem to do anything at this point. Does the comment still
> apply?
Actually, that's probably the whole point of this - to do nothing.
This changes the behaviour of the idle loop from using the WFI to
just spinning instead with no wait-for-interrupt or anything else.
We just keep reading the need_resched flag.
That's much better than the commented out code which opens a mighty
big race condition which will then give bad scheduling behaviour,
allowing the idle task to sleep in WFI until the next interrupt while
the need_resched flag may be set.
Sure, there's better ways to do this, via the disable_hlt() stuff,
and whatever its replacement implementation is now called. But
ultimately this workaround really is about "doing nothing" when
idle!
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