USB autosuspend in F12
Matthew Garrett
mjg at redhat.com
Tue Jun 9 18:32:02 UTC 2009
USB is an irritating protocol that requires USB controllers to remain
active whenever a device is attached, even if that device is doing
nothing. This consumes unnecessary power and can prevent the system
going into deep idle states under some circumstances. The kernel
supports USB autosuspend, which allows idle USB devices to be suspended
and the upstream ports to power down. This is disabled by default
because it breaks various pieces of hardware.
Through F12 I'm going to be slowly enabling autosuspend on various
pieces of USB hardware. The aim is to ensure that it's only enabled on
hardware that supports it. This is going to be a combination of kernel
modifications and packaging changes, and while I'll be testing as many
as possible before uploading anything there's a risk that some hardware
will misbehave. I'll let people know when I think I'm about to upload
anything risky.
The first part of this is an upload of libfprint which enables
autosuspend on fingerprint readers. I'm expecting this to be pretty
safe, but there's always the possibility that a couple of people will
find problems. If your fingerprint reader suddenly stops working after
this change, please file a bug and include the output of lsusb.
--
Matthew Garrett | mjg59 at srcf.ucam.org
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