Re: [PATCH 03/12] arm: omap3: Only sleep in cpuidle driver if I/O wake-ups work

["Mark A. Greer" <mgreer@animalcreek.com>]

On Fri, Apr 27, 2012 at 02:12:12PM -0700, Kevin Hilman wrote:
> "Mark A. Greer" <mgreer@animalcreek.com> writes:
> 
> > On Tue, Apr 24, 2012 at 01:51:05PM -0700, Mark A. Greer wrote:

> > Just thinking out loud...
> >
> > We could chose whether pm_idle & cpuidle issue a wfi based on
> > whether there is a davinci-emac present.  The issue with that is
> > that someday there may be another SoC that has a davinci-emac that
> > can wake up the system.  I know cpu_is_xxx() is frowned upon but
> > this does seem like a proper usage of it--the deciding factor
> > really is whether its an am35x or not (and CONFIG_TI_DAVINCI_EMAC
> > is enabled).
> 
> The presence of the davinci_emac is probably overkill, avoiding WFI
> should really only be done when the davinci_emac is *active*.
> e.g. using an am35x with an EMAC *present*, but not in use because
> there's an MMC rootfs for example.
> 
> If there's a good way to detect an in-use davinci_emac, then
> disable_hlt() can be used to avoid WFI.  When the davinci_emac is not in
> use (e.g. module unloaded etc.) then enable_hlt() can be used to
> (re)allow WFI.

This can work for pm_idle but what should be done for cpu_idle
(as in, omap3_enter_idle[_bm])?  We should have some sort of
solution for that so users can safely enable CONFIG_CPU_IDLE
and not have the am3517 fall apart.

Mark