i.MX ProcessorsのトピックRe: Has any one used Suspend to RAM in Linux?

Has any one used Suspend to RAM in Linux?

MichaelOlsen — Wed, 31 Aug 2011 07:35:00 GMT

Hi,

I am researching the possibilities of power management for Linux on the i.mx28, and in the documents from Freescale they mention that Suspend to RAM is not implemented.

I am wondering if any one else have required this mode and implemented it?

Re: Has any one used Suspend to RAM in Linux?

RobertSchwebel — Wed, 31 Aug 2011 07:54:37 GMT

Hi Michael,

Can you elaborate the intention behind your question? Why do you want to suspend an embedded system, instead of just booting it?

Best regards,

Robert

Re: Has any one used Suspend to RAM in Linux?

MichaelOlsen — Wed, 31 Aug 2011 08:12:39 GMT

Hi Robert,

We want to put execution on hold and wait until an event (for example an input is changed) before resuming again.

This can be done with suspend, however the power consumption in this mode is to large.

Best regards,

Michael

Re: Has any one used Suspend to RAM in Linux?

RobertSchwebel — Wed, 31 Aug 2011 08:45:09 GMT

Ok, so booting quickly is no option for you, too bad :-)

I can only comment for the mainline kernel, not for the Freescale kernel, and in mainline we unfortunately don't have the sophisticated power management functions for the MX28 yet.

rsc

Re: Has any one used Suspend to RAM in Linux?

MichaelOlsen — Wed, 31 Aug 2011 09:58:18 GMT

A fast bootup time is always appreciated :-)

In this case, we want an application to enable the Suspend, and when the system wakes, the application must resume from that point.

I assume that the mainline kernel you mention is for the i.mx28. Are you using the freescale drivers? or making your own?

Re: Has any one used Suspend to RAM in Linux?

RobertSchwebel — Wed, 31 Aug 2011 10:14:20 GMT

Michael,

We are working on the official kernel on kernel.org and have done a lot of work to bring the MX28 into this kernel. It is not feature complete, but this will improve over the time, as either we will port more drivers as a part of our customer projects, or others in the community will provide code.

So it is neither "our" drivers nor Freescales, it is just what you can see in the public trees.

Robert

Re: Has any one used Suspend to RAM in Linux?

dot_bob — Wed, 31 Aug 2011 17:25:22 GMT

What power consumption requirements are you trying to achieve?

So far the lowest I have been able to achieve and still have the capability to resume is about 45mW.

-Rob

Re: Has any one used Suspend to RAM in Linux?

MichaelOlsen — Thu, 01 Sep 2011 06:17:10 GMT

Hi Rob,

We are trying to get the power consumption down below 100 uA, but with the requirements to keep the ram going we will be happy with a power consumption under 1 mA.

Rob Taylor said:

What power consumption requirements are you trying to achieve?

So far the lowest I have been able to achieve and still have the capability to resume is about 45mW.

-Rob