[Gta04-owner] Crowdfunding an Ubuntu smartphone

Rainer Dorsch rdorsch at web.de
Mon Aug 26 22:14:03 CEST 2013


On Monday 26 August 2013 13:32:41 joerg Reisenweber wrote:
> On Mon 26 August 2013 13:17:09 Radek Polak wrote:
> > On Saturday, August 24, 2013 03:20:10 PM joerg Reisenweber wrote:
> > > On Sat 24 August 2013 14:22:55 Radek Polak wrote:
> > > > 1/ poor power management
> > > 
> > > [...]
> > > 
> > > > something. But i always worked in userspace. I barely understand
> > > > kernel
> > > > and i have no EE skills and equipment to contribute. I can contribute
> > > > only as a tester. I thought that i will deliver working userspace and
> > > > IMO QtMoko is very good at it. But without working kernel and HW there
> > > > is not much point to improve it.
> > > 
> > > many thanks for this contribution, it's already a better help than much
> > > of the discussion about what's wrong with our community and the GTA04
> > > project at large.
> > > 
> > > However one remark about it: it's not that simple to blame kernel for
> > > poor power management. What we learned from last maybe 6 years of
> > > different OM distros and from maemo and mer and nitdroid etc is: poor
> > > power management is way too often caused by userland, like sensorfw and
> > > WLAN connection manager and X11/windowmanager and audio (alsa/PA) and
> > > whatnot else.
> > 
> > Yup, after playing with alsa settings i could save a few mAmps on GTA04
> > too.
> > 
> > > Often it's even rogue apps that do silly stuff like updating their
> > > system
> > > status icon 25 times per second or constantly chatting with internet or
> > > even just polling files when you should use inotify instead.
> > > Kernel power saving measures are relatively simple to test and fix, and
> > > usually it's not kernel to blame for abysmal standby time and/or
> > > operation time.
> > > 
> > > To give you a simple example: on N900 maemo you have "scanning period"
> > > in
> > > settings-internet, which makes device scan for WLAN APs only every 5,
> > > 10,
> > > ... even 30 min. This is needed since the WLAN chip cuts thru the
> > > battery
> > > in less than 3 hours when you constantly scan for APs. Clearly a
> > > userland
> > > issue where kernel can't do much. Now you can start to blame kernel WLAN
> > > driver for not doing proper powersaving but that won't help establish a
> > > decently working usable OS on N900.
> > 
> > I think in case of QtMoko on GTA04 we can blame kernel/HW a little bit
> > more, since we are using suspend to RAM whereas N900 is always on (which
> > really cool btw). So while GTA04 is in standby there should be idealy just
> > PMU+RAM+modem turned on, everything else should be off. But something is
> > wrong and noone has yet figured what it is. At best there is ~16mA with
> > omap enable_off_mode - but then we hit "imprecise external abort" bug so
> > currently we have ~22mA at best. If you compare this with GTA02 or N900
> > it's really bad. GTA02 is 12mA and i'd say N900 is even better. Together
> > with reenumerating modem it makes GTA04 barely usable even for a few
> > hardcore supporters but unusable for normal users.
> > 
> > Regards
> > 
> > Radek
> 
> Yes, absolutely (I can't confirm neither deny your facts). N900 easily goes
> down to ~10mA in *standby*, see
> http://wiki.maemo.org/N900_Hardware_Power_Consumption
> and also
> http://wiki.maemo.org/N900_software_power_management
> 
> What I can think of are floating lines making chips eat more than they
> should - may particularly due to suspend mode.
> 
> Let's hope we'll iron that out during next few months
> 

I did some measurements on my n900 with the battery chip and it shows 2-3 mA 
power consumption in airplane mode (i.e. all radios off).

Rainer


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Rainer Dorsch
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