Re: udev USB autosupend whitelist (was Re: [PATCH] Bluetooth: btusb: Restore QCA Rome suspend/resume fix with a "rewritten" version)

[Hans de Goede]

Hi,

On 16-02-18 17:49, Brian Norris wrote:
> + Benson (and there are probably others that know better answers)
>
> Hi,
>
> On Fri, Feb 16, 2018 at 09:26:37AM +0100, Hans de Goede wrote:
> > Going a bit off-topic here, so changed the subject.
> > I will reply on topic in another mail.
> >
> > On 16-02-18 03:27, Brian Norris wrote:
> > > I use a set of udev rules that manually whitelist devices for
> > > autosuspend. You can see it here:
> > >
> > > https://chromium.googlesource.com/chromiumos/platform2/+/43728a93f6de137006c6b92fbb2a7cc4f353c9bf/power_manager/udev/gen_autosuspend_rules.py#83
> > >
> > > You'll find at least one Rome chip in there.
> >
> > Oh, that is a very interesting link for the work I've been doing to
> > improve Linux power-consumption in general:
> >
> > https://fedoraproject.org/wiki/Changes/ImprovedLaptopBatteryLife
> >
> > I was actually planning on at least doing such a list for WWAN modems,
> > for btusb my approach has been to just enable it everywhere
> > (except for QCA devices as I got bugreports for those).
> >
> > Note that I plan to eventually submit this whitelist to the
> > udev rules which are part of systemd upstream, so if chromeos
> > is using systemd too, this is something to be aware of for you.
>
> Chrome OS does not currently use systemd, but thanks for the heads up.
>
> > Question, is the white-listing of the root and rate-limiting
> > hubs really necessary? I thought these have this enabled by default?
>
> This list is old and maintained by several of my team, originating from
> quite a ways back (i.e., much older kernels). It's quite possible that
> some of it is redundant today.

Ok, I double checked and it seems that explicitly setting power/control
to auto for any USB hub is not necessary as they all default to auto
now.

So FWIW you may want to consider removing this.

Regards,

Hans