[PATCH 00/20] powerpc: Convert power off logic to pm_power_off

Geert Uytterhoeven geert at linux-m68k.org
Thu Oct 2 00:33:34 EST 2014

Hi Alex,

On Wed, Oct 1, 2014 at 3:27 PM, Alexander Graf <agraf at suse.de> wrote:
> The generic Linux framework to power off the machine is a function pointer
> called pm_power_off. The trick about this pointer is that device drivers can
> potentially implement it rather than board files.
> Today on PowerPC we set pm_power_off to invoke our generic full machine power
> off logic which then calls ppc_md.power_off to invoke machine specific power
> off.
> However, when we want to add a power off GPIO via the "gpio-poweroff" driver,
> this card house falls apart. That driver only registers itself if pm_power_off
> is NULL to ensure it doesn't override board specific logic. However, since we
> always set pm_power_off to the generic power off logic (which will just not
> power off the machine if no ppc_md.power_off call is implemented), we can't
> implement power off via the generic GPIO power off driver.
> To fix this up, let's get rid of the ppc_md.power_off logic and just always use
> pm_power_off as was intended. Then individual drivers such as the GPIO power off
> driver can implement power off logic via that function pointer.
> With this patch set applied and a few patches on top of QEMU that implement a
> power off GPIO on the virt e500 machine, I can successfully turn off my virtual
> machine after halt.

This is touching the same area as last night's
"[RFC PATCH 00/16] kernel: Add support for poweroff handler call chain"



Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

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