[Community] GTA04A5 / Letux 2804

Dr. H. Nikolaus Schaller hns at goldelico.com
Thu Jan 16 19:09:16 CET 2014


Hi,

Am 16.01.2014 um 18:01 schrieb Rico Rommel:

> Am Donnerstag, 16. Januar 2014, 12:08:07 schrieb Dr. H. Nikolaus Schaller:
>> Am 16.01.2014 um 11:42 schrieb Radek Polak:
>>> On Thursday, January 16, 2014 11:21:39 AM Dr. H. Nikolaus Schaller wrote:
>>>> Ok, please help to fix the power management (in the latest kernel
>>>> because
>>>> everything else makes no sense to me and is unlikely to get outside
>>>> support).
>>> 
>>> I dont know how good/bad is PM in 3.12 kernel. But IIRC last time it was
>>> much worse then 3.7. So the starting point could be to compare 3.7 and
>>> 3.12 and get the PM to the level it is in 3.7.
>> Hm. I think the starting point should be to check if your assumption that
>> 3.12 is worse is still correct with the 3.12.7 kernel. Also because in the
>> 3.12.7 kernel we have included all the 3.7 kernel patches.
>> 
>> There are three potential reasons:
>> a) at the time you tested there might have been a kernel bug, that may have
>> been fixed by now (or may be still be open) b) we may have damaged one of
>> the 3.7 improvements while merging/rebasing c) someone (in the Linux kernel
>> community) has rewritten a kernel driver that we use and that now draws
>> more mA.
>> 
>> Most likely it is a single subsystem that does not work correctly any more.
>> 
>> But without testing we will never know if it is really worse.
> 
> I think, it's even worse than Radek says.
> 
> Last Weekend i played around with kernel 3.12.7 and did a trip to make some 
> GPS-tracks. It started with approximately 200 mA and increased within 3 hours 
> to > 400 mA. The increase is also be observed with kernel 3.7, but not in this 
> extend.
> 
> Btw, after copying the modules to the phone, i forgot to build the module-
> deps, so no modules were loaded at boot time. Power consumption was < 100 mA 
> in idle with display on. After loading modules and restarting fso-daemons, 
> current increased to > 200 mA.

Ok.

> It was  reproducable multiple times after removing battery before powering on.
> 
> While starting fsodeviced + fsousaged is powering devices on and off, so 
> something seems to not power down correctly.

Can you better find out what the "something" is?

> Another problem is the camera driver. if it's loaded cpu doesn't enter higher 
> C-States.

I think the 3.7 has no camera driver at all and I think nobody has analysed the
camera driver for power management. The V4L2 is a quite complex beast...

But the camera driver chip is disabled in suspend (there are some kernel
log messages telling about reset/initialization).

> It was already mentioned here:
> http://lists.goldelico.com/pipermail/gta04-owner/2013-November/005152.html
> 
> There was a userspace problem, but I have no application, which is accessing 
> the camera.
> 
> Another difference from 3.12 to 3.7 is, that there is a new itg3200 driver that 
> can't be turned off by setting sampling rate to 0. Maybe it keeps cpu from idle 
> by delivering constantly data.

Ok, this all are topics that can be addressed. But please don't expect that they
solve magically.

Patches are welcome!

BR,
Nikolaus




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