Re: [PATCH 1/1] meta-yocto: remove apm from beagleboard MACHINE_FEATURES

[Bruce Ashfield <bruce.ashfield@windriver.com>]

On 11-08-11 7:47 PM, Richard Purdie wrote:
> On Thu, 2011-08-11 at 15:16 -0400, Bruce Ashfield wrote:
>> Fixes [YOCTO: #916]
>>
>> apm is not something that we require in our yocto reference beagleboard
>> BSP. It currently is listed in the MACHINE_FEATURES for the board, which
>> leads to the runtime message:
>>
>>    Starting advanced power management daemon: No APM support in kernel
>>
>> Since "/proc/apm" is not present. The board config we are targeting does
>> not have the hardware to back this, so adding the emulation support
>> wouldn't yield useful data. We'll leave this extended functionality for
>> other more appropriate beagleboard configs.
>
> On arm it used to be the case that this was the only way to expose user
> interface to suspend/resume the machine. Its not so much about their
> being hardware present for it as the whole kernel side was emulation of
> the user space notification part.
>
> Has something changed in recent kernels in this area?

I won't claim to be an expert here .. but I haven't used apmd
on many machines in quite a while. Assuming suspend_ops is
implemented, it is typically just something ike this:

  echo mem > /sys/power/state

    or

  echo standby > /sys/power/state

With a wakeup via the rtc, or whatever the board offers. I'm
cc'ing Liming on this, since he's been poking at the board recently
and may have more hands on information to share.

If we ARE removing this capability, then we'll take the other option
that we had for this case and enable the emulation.

Cheers,

Bruce




>
> Cheers,
>
> Richard
>
>
>