Re: Changes to power management in ehci-tegra

[Stephen Warren <swarren@xxxxxxxxxxxxx>]

On 04/13/2012 01:46 PM, Alan Stern wrote:
> On Fri, 13 Apr 2012, Stephen Warren wrote:
>> I've tested the patch, and can unplug a USB device, wait 10 seconds,
>> then plug it back in, and everything works as expected.
>>
>> However, I don't notice /sys/devices/.../power/runtime_status ever
>> saying anything other than active, and I can't cat autosuspend_delay_ms,
>> so I assume I'm still not triggering the path you want me to test. I do
>> have PM_RUNTIME turned on. Any ideas? Do I need some patch to the USB
>> core to enable this? I tested on next-20120413 plus a few local patches.
> 
> autosuspend_delay_ms isn't relevant here; the controller should be 
> suspended with no delay as soon as the root hub suspends.  No other 
> patches should be needed; it sounds like you're doing everything right.
> 
> If you enable CONFIG_PM_ADVANCED_DEBUG along with CONFIG_PM_RUNTIME, 
> what do all the other power/runtime_* files show?

The EHCI controller's active_kids count stays at 1 all the time. I
assume that's the root USB hub device. Looking in its power/ directory,
I see that even when nothing is plugged in, runtime_status==enabled,
even with no active_kids or runtime_usage:

[  242.611209] usb 3-1: USB disconnect, device number 4
root@ilyich:/sys/devices/tegra-ehci.2/usb3/power# cat async
enabled
root@ilyich:/sys/devices/tegra-ehci.2/usb3/power# cat autosuspend_delay_ms
0
root@ilyich:/sys/devices/tegra-ehci.2/usb3/power# cat control
auto
root@ilyich:/sys/devices/tegra-ehci.2/usb3/power# cat runtime_active_kids
0
root@ilyich:/sys/devices/tegra-ehci.2/usb3/power# cat runtime_active_time
262840
root@ilyich:/sys/devices/tegra-ehci.2/usb3/power# cat runtime_enabled
enabled
root@ilyich:/sys/devices/tegra-ehci.2/usb3/power# cat runtime_status
active
root@ilyich:/sys/devices/tegra-ehci.2/usb3/power# cat
runtime_suspended_time
0
root@ilyich:/sys/devices/tegra-ehci.2/usb3/power# cat runtime_usage
0

Are the wakeup_* files in this directory relevant? wakeup says
"disabled", and all the others are empty.
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