[PATCH 2/2] ARM: S5PV310: Update CPU hotplug implementation

[Russell King - ARM Linux]

On Thu, Sep 30, 2010 at 10:02:37AM -0700, Colin Cross wrote:
> On Wed, Sep 29, 2010 at 4:58 AM, Kukjin Kim <kgene.kim at samsung.com> wrote:
> > Kukjin Kim wrote:
> >>
> >> From: Changhwan Youn <chaos.youn at samsung.com>
> >>
> >> This patch updates CPU hotplug implementation to reduce CPU power
> >> consumption
> >> and will turn off the CPU power when CPU1 is unplugged while previous CPU
> >> hotplug
> >> used CPU idle.
> >> This patch removes init memory freeing code to use CPU boot code when CPU1
> > is
> >> plugged-in again and adds vfp_enable() call to allow to access CP10 and
> > CP11.
> >>
> >> Signed-off-by: Changhwan Youn <chaos.youn at samsung.com>
> >> Signed-off-by: Kukjin Kim <kgene.kim at samsung.com>
> >> Cc: Russell King <rmk at arm.linux.org.uk>
> > Cc: Tony Lindgren <tony at atomide.com>
> > Cc: Colin Cross <ccross at android.com>
> > Cc: Erik Gilling <konkers at android.com>
> > Cc: Olof Johansson <olof at lixom.net>
> >
> 
> snip
> 
> >> +#ifndef CONFIG_HOTPLUG_CPU
> >>       if (!machine_is_integrator() && !machine_is_cintegrator())
> >>               totalram_pages +=
> > free_area(__phys_to_pfn(__pa(__init_begin)),
> >>                                           __phys_to_pfn(__pa(__init_end)),
> >>                                           "init");
> >> +#endif
> >>  }
> >>
> >>  #ifdef CONFIG_BLK_DEV_INITRD
> 
> I don't think this is necessary.  Any symbol that is necessary for CPU
> hotplug should be marked with __cpuinit instead of __init.  The linker
> script will put __cpuinit symbols outside the __init_begin -
> __init_end section if CONFIG_HOTPLUG_CPU is enabled.

That's the theory, but not everything required for a complete restart of
a secondary CPU (iow, if it's powered off) is in the right section yet.
I'll have patches hopefully tomorrow to address this.