Patrick Häcker [2014-11-05 16:55 +0100]: > I you want to have permanent power saving activated for your devices, the > recommended way is to use udev (e.g. > https://wiki.archlinux.org/index.php/Power_saving#USB_autosuspend). Some > [...] > - Is there already something like this?
By coincidence I recently noticed something interesting in sysfs: My
USB devices seem to have an attribute "supports_autosuspend". These
are all 1 except for my USB webcam [1] where it is 0. This sounds very
promising indeed! So apparently the kernel now already grew either a
heuristics or some black/whitelists?
At least the current state how Linux (3.16.0) and udev (215) configure
autosuspend seems a bit weird:
- Some of my USB devices have power/autosuspend == "2": internal
laptop webcam, USB webcam ([1] again), USB Keyboard, USB mouse.
All others have "0". There is no udev rule or other thing on my
system to set those, so unless it's udev or systemd itself I guess
it's from the kernel.
- Most of my USB devices have power/level=="auto" (i. e. suspend
enabled), only some of them are "on" (i. e. suspend disabled).
Curiously those which are "on" are three of above devices where
autosuspend==2: USB webcam, USB Keyboard, USB mouse.
- The only udev rule which I'm aware of that does autosuspend is
42-usb-hid-pm.rules:
ACTION=="add", SUBSYSTEM=="usb", ATTR{bInterfaceClass}=="03",
ATTRS{removable}=="fixed", TEST=="../power/control",
ATTR{../power/control}="auto"
So it does not seem to be the case that we don't currently enable
autosuspend at all, but it's currently highly inconsistant and
confusing.
Martin
[1]
E: ID_MODEL=08af
E: ID_MODEL_FROM_DATABASE=QuickCam Easy/Cool
E: ID_VENDOR=046d
E: ID_VENDOR_FROM_DATABASE=Logitech, Inc.
--
Martin Pitt | http://www.piware.de
Ubuntu Developer (www.ubuntu.com) | Debian Developer (www.debian.org)
signature.asc
Description: Digital signature
_______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
