[Letux-kernel] power management problems in ehci-omap

Andreas Kemnade andreas at kemnade.info
Mon Feb 5 09:23:30 CET 2018


On Sun, 4 Feb 2018 11:55:02 +0100
Michael Nazzareno Trimarchi <michael at amarulasolutions.com> wrote:

> Hi Andreas
> 
> On Sun, Feb 4, 2018 at 11:50 AM, Andreas Kemnade <andreas at kemnade.info> wrote:
> > Hi,
> >
> > On Sun, 4 Feb 2018 09:43:45 +0100
> > Michael Nazzareno Trimarchi <michael at amarulasolutions.com> wrote:
> >  
> >> Hi Andreas
> >>
> >> On Sun, Feb 4, 2018 at 9:38 AM, Andreas Kemnade <andreas at kemnade.info> wrote:  
> >> > On Sun, 4 Feb 2018 00:10:50 +0100
> >> > Michael Nazzareno Trimarchi <michael at amarulasolutions.com> wrote:
> >> >  
> >> >> Hi
> >> >>
> >> >> On Sun, Feb 4, 2018 at 12:03 AM, Andreas Kemnade <andreas at kemnade.info> wrote:  
> >> >> > Hi,
> >> >> >
> >> >> > I booted a 4.15 kernel without udev and loaded modules piece by piece to analyze
> >> >> > pm problems. modprobe ehci-omap increases current by around 35mA and
> >> >> > also rmmod ehci-omap does not let it go down at all.
> >> >> >
> >> >> > I expect that removing hardware does the same thing  
> >> > nonsense sentence from me, was to tired. I would expect that removing the modules
> >> > properly powers down the device.  
> >> >> >
> >> >> > Also suspend current increases by around 15mA if that module is loaded.
> >> >> > I tested with having everything disabled which is attached to that usb bus.
> >> >> >  
> >> >>
> >> >> Do you have an LTE connected to the usb?
> >> >>  
> >> > Yes, there is a UMTS modem attached, but it was off during the tests.
> >> > It did not enumerate on the modem.
> >> >  
> >>
> >> Just to understand if the suspend current drop was connected to the
> >> suspend of lte modem on your side.
> >> So you don't have anything connected on usb bus?
> >>  
> > Suspend current is increased when the ehci-omap module is loaded
> > in comparison to the state. I tested with the modem disabled, so there
> > is nothing on the bus. Increased suspend current is one thing,
> > current_before_modprobe_ehci_omap != current_after_rmmod_ehci_omap.
> >
> > I am testing with init=some_testscript.sh, so no userspace
> > is doing strange things. No module autoload or something.
> >  

Ok, there is some heavy EBCAK involved. I just did an
echo rmmod
without a real rmmod. But the suspend thing is still valid.

Sorry for the confusion.

To avoid further confusion I have uploaded these two scripts
I have given to the kernel.
http://misc.andi.de1.cc/measure4.sh

output from that:
no modules: cur: 61047 delta: 61047
before: 423462
after: 421326
average 25632 uA over 300 seconds
 cur: 60333 delta: -714
+ehci-omap cur: 93712 delta: 33379
-ehci-omap cur: 60511 delta: -33201
before: 420792
after: 418656
average 25632 uA over 300 seconds


http://misc.andi.de1.cc/measure5.sh
output from that:

no modules: cur: 61225 delta: 61225
before: 427734
after: 425598
average 25717 uA over 299 seconds
 cur: 59797 delta: -1428
+ehci-omap cur: 93712 delta: 33915
before: 425242
after: 421860
average 40719 uA over 299 seconds

The 40mA is too high. We have had measurements below 30mA even with
modem enabled with some pre-dt setup (Kernel 3.7)

Regards,
Andreas
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 833 bytes
Desc: OpenPGP digital signature
URL: <http://lists.goldelico.com/pipermail/letux-kernel/attachments/20180205/cddd7fbd/attachment.asc>


More information about the Letux-kernel mailing list