On Friday 10 September 2004 3:14 pm, Mirko Selent wrote:
> ....
> This document describes power saving by using selective suspend instead
> of interrupt polling transfer when a mouse is attached for example.
Interesting writeup, though it's a bit XP-centric. Don't they know
that The Future Is Linux? :)
It's also a bit oversimplified, but that's a different issue. Laptop
with single mouse isn't an uncommon config.
> My question is, will be implemented this feature into Linux-USB?
It'll start working shortly after someone submits HID driver patches,
for 2.6.9-rc1 or later, that:
- Provide a suspend() callback that kills its interrupt
transfer, and a resume() method that reissues it.
Debug this with /sys/bus/usb/.../power/state and almost any
USB hub; I've used external ones, OHCI, and EHCI there,
but to use UHCI I think you'll need patches that aren't yet
in Linus' tree (maybe they'll be in rc2). And a HID device.
- Add a timer to make a new "idle" timeout (5 seconds in that
writeup) make a task call usb_suspend_device(), of the config
supports remote wakeup.
Debug this once HID suspend/resume works, using some device
that supports remote wakeup; not all mice or keyboard do,
and some will lie about it.
The 2.6.9 kernels add CONFIG_USB_SUSPEND for selective suspend
and remote wakeup, and /proc/acpi/wakeup for some important
non-USB/non-PCI parts of remote wakeup. But that's all new, and
the parts aren't yet fully integrated with each other. There are bugs
to be found and fixed, that's why CONFIG_USB_SUSPEND is flagged
as EXPERIMENTAL for now ... it'll take a while to settle down. HID
isn't the only USB driver that needs PM updates.
Want to start working on the patches? I'd really like to see the
first part working soon. Once that's working, and a few more
PM integration issues get resolved, that will let USB keyboards
and mice wake up systems in suspend-to-RAM (or standby)
power states.
- Dave
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