linux-kernel - Re: Droid 4: suspend to RAM?

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Date:   Wed, 8 Aug 2018 23:32:04 +0200
From:   Pavel Machek <pavel@....cz>
To:     Tony Lindgren <tony@...mide.com>
Cc:     Michael Nazzareno Trimarchi <michael@...rulasolutions.com>,
        kernel list <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Linux OMAP Mailing List <linux-omap@...r.kernel.org>,
        Sebastian Reichel <sre@...nel.org>, nekit1000@...il.com,
        mpartap@....net, Merlijn Wajer <merlijn@...zup.org>
Subject: Re: Droid 4: suspend to RAM?

On Wed 2018-08-08 02:05:12, Tony Lindgren wrote:
> * Pavel Machek <pavel@....cz> [180727 11:35]:
> > Hi!
> > > > > high even before modem (and thus USB) is enabled.
> > > > >
> > > > > Interestingly, CyanogenMod and Jolla seem to have higher power
> > > > > consumption than stock operating system.
> > > > >
> > > > > (My Linux can survive for 10 hours, stock system could survive for 4
> > > > > days if I'm not mistaken).
> > > > >
> > > > > I thought I would experiment with suspend to RAM.. and it indeed
> > > > > seemed to suspend ok, but I could not wake it up. Do I need to set up
> > > > > wakeup with button somehow? Is suspend to RAM required for good power
> > > > > consumption?
> > > > 
> > > > Sorry but pm subsystem has debug mode that you can test in a easy way.
> > > > You can even wakeup by any rtc alarm easily.
> > > 
> > > Yes, that is how it works on PC (but there power button works,
> > > too). Is it expected to work on Droid in v4.18?
> > 
> > I tried setting up wakeup using RTC, but no, it does not seem to work:
> > 
> > root@...uan:/my/tui/d4# rtcwake -m no -s 5
> > rtcwake: wakeup using /dev/rtc0 at Fri Jul 27 11:28:44 2018
> > root@...uan:/my/tui/d4# echo mem > /sys/power/state
> 
> Works for me here as tested on next-20180808, maybe you don't have
> CONFIG_RTC_DRV_CPCAP? Maybe you are trying to use
>CONFIG_RTC_DRV_OMAP?

I tried with mainline... there will be no graphics in next, right? And
yes, I had CONFIG_RTC_DRV_CPCAP and not CONFIG_RTC_DRV_OMAP.

> Then for deeper idle modes, you need to also idle UARTs, and unbind or
> unload USB related modules. You should get to something like 160mW
> power consumption with mdm6600 enabled and SoC suspended that way.

That's slightly interesting. echo mem > /sys/power/state should do all
the work, right? Disable UARTs etc. Plus, is 160mW still a bit high?

> Then again system running idle is about the same with timers and
> interrupts working so I'd just idle UARTs and unload USB modules :)
> 
> My UART idle script below for reference.

Thanks, let me try...

								Pavel
								
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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