Re: Cannot shutdown power use from built in webcam in thinkpad T530 questions]

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On Wed, 18 Sep 2013, Marc MERLIN wrote:

> Howdy,
> 
> I have a T530 with a built in webcam that uses the uvcvideo driver.
> Kernel 3.10.6, but the problem has been there for many kernel versions.
> 
> From time to time (not always) it shows up at the top of powertop with
> an unexplained high power use while I'm not using the camera.
> Powertop says autosuspend is active:
> Note that tunables says:
>    Good          Autosuspend for USB device Integrated Camera [Chicony Electronics Co., Ltd.]
> 
> Unloading uvcvideo makes no difference. However if I never load uvcvideo
> and never use the camera after booting the laptop, then the device
> doesn't use any power.
> This is better than nothing, but not very desirable since I do use the
> camera from time to google for video conferencing.
> 
> Here's the module info
> gandalfthegreat:/sys/bus/usb/drivers/uvcvideo# l
> total 0
> drwxr-xr-x  2 root root    0 Sep 18 17:48 ./
> drwxr-xr-x 12 root root    0 Sep 17 15:10 ../
> lrwxrwxrwx  1 root root    0 Sep 18 21:30 3-1.6:1.0 -> ../../../../devices/pci0000:00/0000:00:1a.0/usb3/3-1/3-1.6/3-1.6:1.0/
> lrwxrwxrwx  1 root root    0 Sep 18 21:30 3-1.6:1.1 -> ../../../../devices/pci0000:00/0000:00:1a.0/usb3/3-1/3-1.6/3-1.6:1.1/
> --w-------  1 root root 4096 Sep 18 21:30 bind
> lrwxrwxrwx  1 root root    0 Sep 18 21:30 module -> ../../../../module/uvcvideo/
> -rw-r--r--  1 root root 4096 Sep 18 21:30 new_id
> -rw-r--r--  1 root root 4096 Sep 18 21:30 remove_id
> --w-------  1 root root 4096 Sep 18 17:48 uevent
> --w-------  1 root root 4096 Sep 18 21:30 unbind
> 
> gandalfthegreat:/sys/bus/usb/devices/3-1.6/power# grep . *
> active_duration:61227648
> async:enabled
> autosuspend:2
> autosuspend_delay_ms:2000
> connected_duration:66830880
> control:auto
> level:auto
> persist:1
> runtime_active_kids:0
> runtime_active_time:18870052
> runtime_enabled:enabled
> runtime_status:active
> runtime_suspended_time:5324088
> runtime_usage:0

This all looks correct.

> Any ideas?

You might get more information from a kernel with CONFIG_USB_DEBUG 
enabled.  Especially if you add

#define VERBOSE_DEBUG

to drivers/usb/core/driver.c before the first #include line.

Alan Stern

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