[Gta04-owner] Modem off

Andreas Kemnade andreas at kemnade.info
Mon Nov 4 23:09:27 CET 2013


Hi,

On Sat, 2013-09-21 at 08:19 +1000, NeilBrown wrote: 
> On Fri, 20 Sep 2013 15:00:28 +0200 Radek Polak <psonek2 at seznam.cz> wrote:
> 
> > On Thursday, September 19, 2013 03:47:47 AM NeilBrown wrote:
> > 
> > > I have some more evidence.
> > > 
> > > I currently have ehci_hcd compiled as a module, so it needs to be loaded
> > > before the modem can be seen.
> > > 
> > > On a fresh reboot of 3.7 without loading the module or toggling the GPIO to
> > > turn on the 3G modem, I see a current draw during suspend of 21.6mA and
> > > 23.7mA If I then "insmod ehci_hcd" the suspend-time current usage goes up
> > > to  30.1mA and 32.2mA.
> > > I then "rmmod ehci_hcd" and the current drops to 12.9 and 15.1 mA.
> > > 
> > > So in each case I see two different measurements with a 2.1mA difference.
> > > 
> > > Loading the module turns something on which was only partly one before.
> > > Removing the module turns it off properly.
> > > 
> > > If I can get "suspend" to turn off whatever "rmmod" turns off, we might be
> > > able to get power usage down by several milliAmps.
> > > 
> > > If anyone else would like to try this and report the results I would love
> > > to hear them.
> > > You need to set:
> > > 
> > > CONFIG_USB_EHCI_HCD=m
> > > 
> > > in .config and make sure nothing turns the modem on at boot time.
> > > Then measure the suspend current.  Then insmod and measure it again.  Then
> > > rmmod and measure it a third time.
> > 
> > Hi,
> > i have tested it today. I used qtmoko v55 kernel - the one which has enabled 
> > omap off mode.
> > 
> > Attached is screenshot with graph.
> > 
> > First current is 22mA - after boot.
> > Then there are values 31mA and 32mA - with ehci_hcd module loaded
> > The last values are 16mA 15mA and 15mA - after rmmod ehci_hcd
> > 
> > So i think we have quite similar results.
> 
> Thanks.  It is good to know it isn't just some thing strange that I'm
> doing :-)
> 
> I've experimented with "rmmod ehci_hcd" just before suspend, and "modprobe"
> on resume, but so far that has just caused a mess.
> I've looked at the code, and it is rather complex.
> It has also changed a lot in 3.10.  So I'm going to defer exploring this more
> until I start on 3.10+ again, probably in a couple of weeks.
> 
In 3.12 I get also around 15mA more current in suspend with modem off.
than with modem on. (suspend does not work reliable with that kernel for
me and I have 60mA/85mA current consumption)

In 3.7 with enabled modem
doing "echo ehci-omap.0 >unbind" in
/sys/bus/platform/drivers/ehci-omap
also increases current. (I get 40mA then)
doing "echo echi-omap.0 >bind"
decreases it again to around 20mA.
That is also strange.

Hmm, what a about doing modprobe/rmmod in
modem-poweron.sh/modem-poweroff.sh?

Greetings
Andreas Kemnade





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