Difficulty getting wp7601 to full suspend or sleep mode

1

I’m trying to get the mangOH Red to suspend down to low-as-possible current.
So far with my app stopped it still draws 140mA - 200mA.
I don’t know what is possible but that seems very high for my battery-powered application.

In the Legato doc set under powerMgr I found a troubleshooting section: Problem: System doesn’t suspend.
This section offered the two tests below, which I have tried:

cat /sys/power/wake_lock

With my app stopped, and devMode stopped,

cat /sys/power/wake_lock shows no user-space wakeup sources.

The other suggestion was a lengthy command shown here:

cat /sys/kernel/debug/wakeup_sources | sed -e s/"^ "/“unnamed”/ | awk ‘{print $6 “\t” $1}’ | grep -v “^0” | sort -n

That shows only this one process:
msm_otg
as having a non-zero active_since field, and thus a keep-awake function.

Anyway, I looked for that process with:

ps -e | grep “msm”

but that shows only these, none of which are msm_otg:
14 ? 00:00:00 msm_watchdog
16 ? 00:00:00 smsm_cb_wq
49 ? 00:00:00 msm_serial_hs_0
50 ? 00:00:00 msm_serial_hs_0
144 ? 00:00:00 msm_ipc_router
1152 ? 00:00:00 msm_thermal:fre
1153 ? 00:00:00 msm_thermal:the

I got a sense from other forum threads that msm_otg may have to do with the USB and/or charging circuit. Since I must have the laptop plugged in to perform the queries above, it might be that the msm_otg wake_lock is a wild goose chase. (no way to know if that is still a wake-lock when the usb is disconnected)

Any suggestions for getting the current draw down as low as possible while my app sleeps (or is stopped which I assume is the same thing) would be greatly appreciated.

Thanks,
Jim

2

Hi Jim,

“msm_otg” means USB is active, normally when we unplug/detach the USB cable/connection, or trigger USB Suspend from host PC then this lock will be released.

For your case, do you have UART console access instead of USB?
So you can try unplug USB then check the wake lock state by UART console to confirm.

Or if you can use power supply to monitor the current consumption drop when USB unplug?

Hope it helps.
Thx

3

Hi Lotam,
Yep that helped a bunch.

Thanks!

Jim