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

[Bruce Ashfield]

On 11-08-12 09:07 AM, Richard Purdie wrote:
> On Thu, 2011-08-11 at 20:51 -0400, Bruce Ashfield wrote:
>> 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.
>
> I have a suspicion that certain parts of the sato code do
> assume /dev/apm_bios device emulation is present to get userspace
> notification of suspend/resume events which the above doesn't provide
> last I checked.
>
> Likely this isn't an issue and I think that code in sato (matchbox panel
> app iirc) is toggled by the MACHINE_FEATURES but its certainly worth
> keeping in mind...

Ack'd. We'll have a look at this. Drop my current pull
request, and this can stand a deeper look.

Bruce

>
> Cheers,
>
> Richard
>
>
>