Hi,
On 13-11-17 18:53, Laura Abbott wrote:
On 11/13/2017 07:40 AM, Hans de Goede wrote:
Hi all,
As mentioned before I'm working on trying to improve the OOTB
power-consumption of Fedora Workstation on laptops
(I need to create an F28 feature page for this).
On many laptops the btusb device is the only USB device not
having USB autosuspend enabled, this causes not only the btusb
device but also the USB controller to stay awake, together using
aprox. 0.4W of power. Modern ultrabooks idle around 6W
(at 50% screen brightness), 3.5W for Apollo Lake devices.
0.4W is a significant chunk of this (7 / 11%).
So I would like to enable btusb autosuspend by default, to
make this possible I've submitted the following kernel
patch upstream which has just been merged (queued for 4.16):
https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next.git/commit/?id=86be3c232877b59f08561b256ff7e73ad39b0785
If it is ok with the Fedora kernel team I would like to add
this as a patch to the Fedora kernels for now and set
the new BT_HCIBTUSB_AUTOSUSPEND option to y. This is not
without a risk of regressions, so this is something for
rawhide/F28 only.
Regards,
Hans
I'm concerned about this mostly because it goes through the
USB stack. USB hardware seems to be particularly bad at hardware
power management based on the archives of linux-usb. I don't
have a good alternative though so I'm okay with it going in
as long as we are prepared for a possible influx of bug reports.
Or maybe I'll be wrong and all hardware will just magically
work correctly.
So as I mentioned in my reply to Justin, to clarify this is
NOT about enabling USB autosuspend everywhere. Most bugreports
about USB autosuspend are about mice and keyboards which claim
to implement remote-wakeup (a feature necessary for auto-suspend)
but don't implement it (correctly).
This thread is only about enabling autosuspend for for USB
connected bluetooth receivers.
Anyways as said this was just to clarify and I do share
your worries that even just for btusb this may cause issues,
but there is a significant power-saving to be had here and
only one way to find out if this causes problems. So I will
go ahead and add the patch + the Kconfig option to rawhide.
Regards,
Hans
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