On 06/26/2014 07:39 PM, Carlos E. R. wrote:
On 2014-06-26 19:06, Zeitlinie wrote:
On 06/26/2014 06:36 PM, Thomas Taylor wrote:
This is basically so people can use it for recharging cell phones and cameras or other battery powered USB devices. If that causes a problem with some device plugged into the USB port while the laptop is in a suspended state then unplug the device. This does not use excess battery power as the power supply is always in use if the power cord is plugged in.
Actually it does not depend on if the cord is plugged in or not: power supply through USB remains 'on' even if I pull the power cord.
Yes, I noticed the same thing with my laptop, a Compaq of some years. It is an intentional feature.
In my case, what I had connected was a fan, one of those designed to put the laptop on top. It would have drained the battery faster than I expected if I had not noticed it.
I did not notice it earlier because I use hibernation more than suspend.
To me this does not seem proper functioning. In particular since the BIOS does directly say so: namely, that when USB always-power-on is 'disabled' in BIOS there should not be any power on the USB ports in the suspend state.
The thing is, they leave them active not for charging phones, but to keep devices such as memory sticks in the same state, for very fast startup. Some of these have internal cache, status variables... all lost on power down. To power them down the computer have to inform them in advance of the fact, power the buses down, then on recovery, locate them, and inform them of the reconnect. Some of them the user has to press a button on the devices (my camera, for instance).
my command of English may be utterly broken, but I really don't get this. So next I'm cutting-and-pasting the relevant portion of text from my BIOS setup: ------------------------- "Always On USB [Disabled] Help The USB ports can charge external devices during low power states (standby, hibernate, or power-off). If the system runs on battery mode, this only works in standby state. [Disabled] USB ports are disabled during low power states. [Enabled] USB ports are powered during low power states." ------------------------ I understand from this, that if my system is in standby and, just to be safe, also unplugged from any power outlets, then my USB port should not be able to run fans, or charge phones, or whatever. Yet they do. Actually I'm starting to think it is not related to openSUSE alone. In the meantime I ran linux from two unrelated live-CDs. Both have the same effect: USB just won't shut off. This is really strange.
It may be configurable, though.
If you are using laptop-mode-tools, have a look at the config options.
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