linux-kernel - Re: [PATCH 1/2] HID: logitech-hidpp: add battery support for HID++ 2.0 devices

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Date:	Fri, 08 Jul 2016 01:21:08 +0200
From:	Bastien Nocera <hadess@...ess.net>
To:	Peter Hutterer <peter.hutterer@...-t.net>,
	Jiri Kosina <jikos@...nel.org>,
	Benjamin Tissoires <benjamin.tissoires@...hat.com>,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	Nestor Lopez Casado <nlopezcasad@...itech.com>
Subject: Re: [PATCH 1/2] HID: logitech-hidpp: add battery support for HID++
 2.0 devices

On Wed, 2016-06-29 at 19:28 +1000, Peter Hutterer wrote:
> If the 0x1000 Unified Battery Level Status feature exists, expose the
> battery
> level.
> 
> The main drawback is that while a device is plugged in its battery
> level is 0.
> To avoid exposing that as 0% charge we make up a number based on the
> charging
> status.

This will require changes in UPower, so that it doesn't try to access
the Logitech unifying devices via user-space, and uses the data from
the kernel. Did you already file a bug?

Note that this would also mean losing the "lux" information, but I
don't think that's something we're that interested in exposing.

For example, for a keyboard that recharges via solar panels, at night:

Device: /org/freedesktop/UPower/devices/keyboard_0003o046Do4002x0004
  native-path:          /sys/devices/pci0000:00/0000:00:14.0/usb3/3-10/3-10:1.2/0003:046D:C52B.0003/0003:046D:4002.0004
  vendor:               Logitech, Inc.
  model:                K750
  serial:               197F3F23
  power supply:         no
  updated:              Fri 08 Jul 2016 01:17:40 CEST (95 seconds ago)
  has history:          yes
  has statistics:       no
  keyboard
    present:             yes
    rechargeable:        yes
    state:               discharging
    warning-level:       none
    luminosity:          16 lx
    percentage:          89%
    icon-name:          'battery-full-symbolic'