LED notification

Andy Green andy at openmoko.com
Sun Oct 12 19:00:55 CEST 2008

Hash: SHA1

Sam Kuper wrote:
> 2008/10/12 Kishore <kitts.mailinglists at gmail.com
> <mailto:kitts.mailinglists at gmail.com>>
>     In addition, i would recommend a look a look at multimedia
>     functions. If the
>     device were to play music (mp3) if there were ways to be more power
>     efficient.
> Good point. Am I right in thinking that there was a point during the
> development of Sony-Ericsson's phones (the point being the introduction

I think we are better to try to find a general low power mode of
operation for the CPU somehow than put in special MP3 playback hardware.

But there is a case for a "system management MPU" that provides some
always-on intelligence even when the CPU is down, that may appear in
future.  But for now as far as we got with always-on intelligence is the
LED flashing thing.

PWM is down in suspend... really all that CPU is very much down, the
PLLs are off, there is no peripheral clock.  All there is working is a
kind of "hold" on GPIO state, and the IO pins are still powered.

> I agree; enabling the device to charge when powered down would be a good
> thing. The vast majority of consumers will need to be confident that if

Yes always-on MPU can deliver consistent power behaviours we can't do in
our current way of relying on PMU.  You would basically make the PMU a
slave of the MPU.  Stuff like debricking scheme for a programmable and
so brickable MPU that controls the PMU... needs careful thought.

- -Andy
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