Launchpad has imported 23 comments from the remote bug at
https://bugs.freedesktop.org/show_bug.cgi?id=96572.

If you reply to an imported comment from within Launchpad, your comment
will be sent to the remote bug automatically. Read more about
Launchpad's inter-bugtracker facilities at
https://help.launchpad.net/InterBugTracking.

------------------------------------------------------------------------
On 2016-06-18T06:42:44+00:00 Vincent Bernat wrote:

Created attachment 124584
xorg.log

Hey!

After switching from intel to modesetting, xbacklight doesn't work
anymore:

$ xbacklight = 20
No outputs have backlight property

However, a backlight control is present in sysfs:

/sys/class/backlight/intel_backlight

In Debian:
 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=824987

Reply at: https://bugs.launchpad.net/ubuntu/+source/xorg-
server/+bug/1440891/comments/4

------------------------------------------------------------------------
On 2016-06-24T09:38:09+00:00 Peter B. Jørgensen wrote:

I have the same problem running Arch linux.
xbacklight works with the xf86-video-intel driver, but not without it, even 
though /sys/class/backlight/intel_backlight is still present.

Reply at: https://bugs.launchpad.net/ubuntu/+source/xorg-
server/+bug/1440891/comments/5

------------------------------------------------------------------------
On 2016-07-07T15:20:07+00:00 Timabraldes wrote:

I'm not sure what the etiquette is about "me too" comments in this
Bugzilla instance, but I see the same behavior on a Lenovo Thinkpad
T440s: /sys/class/backlight/intel_backlight is present but xbacklight
simply says "No outputs have backlight property" when I try to run it. I
have not installed the intel driver so I'm using modesetting by default.

Reply at: https://bugs.launchpad.net/ubuntu/+source/xorg-
server/+bug/1440891/comments/6

------------------------------------------------------------------------
On 2016-07-29T07:17:30+00:00 rubik wrote:

Experiencing the same problem. For me it's a real problem because the intel 
driver freezes constantly, so my only option is modesetting.
Is there something I can do to help?

Reply at: https://bugs.launchpad.net/ubuntu/+source/xorg-
server/+bug/1440891/comments/9

------------------------------------------------------------------------
On 2016-08-03T16:09:21+00:00 Martin-peres-n wrote:

Thanks for the bug report, I will be looking it starting from today.

Reply at: https://bugs.launchpad.net/ubuntu/+source/xorg-
server/+bug/1440891/comments/10

------------------------------------------------------------------------
On 2016-08-04T06:27:05+00:00 Jani-nikula wrote:

IIUC xf86-video-intel provides the backlight property itself; such a
property is not supplied by the kernel.

Reply at: https://bugs.launchpad.net/ubuntu/+source/xorg-
server/+bug/1440891/comments/11

------------------------------------------------------------------------
On 2016-08-04T14:46:03+00:00 Martin-peres-n wrote:

(In reply to Jani Nikula from comment #5)
> IIUC xf86-video-intel provides the backlight property itself; such a
> property is not supplied by the kernel.

Indeed. Here is a relevant thread:
https://lists.freedesktop.org/archives/dri-
devel/2014-September/thread.html#67984

Reply at: https://bugs.launchpad.net/ubuntu/+source/xorg-
server/+bug/1440891/comments/12

------------------------------------------------------------------------
On 2016-08-23T10:38:51+00:00 Timo Aaltonen wrote:

so is that set of patches going to be revived soon?

Reply at: https://bugs.launchpad.net/ubuntu/+source/xorg-
server/+bug/1440891/comments/13

------------------------------------------------------------------------
On 2016-09-10T19:42:26+00:00 Nico-freedesktop-org wrote:

I wonder if anyone of the developers is reading here at all?

The only reason not to use the modesetting driver is the missing
backlight capability - as it is faster and more reliable than the intel
driver (for intel hardware!).

Reply at: https://bugs.launchpad.net/ubuntu/+source/xorg-
server/+bug/1440891/comments/14

------------------------------------------------------------------------
On 2016-09-12T15:20:26+00:00 Eero-t-tamminen wrote:

(In reply to nico-freedesktop.org from comment #8)
> I wonder if anyone of the developers is reading here at all?

Martin's soon back from vacation.

I don't see Jani on the CC, but if this needs new API from kernel, bug
about that should be linked here. Is there one?


> The only reason not to use the modesetting driver is the missing backlight
> capability - as it is faster and more reliable than the intel driver (for
> intel hardware!).

You didn't mention in which use-case, on which distro and with which
exact HW you've compared modesetting and Intel DDX performance, but in
our tests Intel DDX has been somewhat faster on average.  As to
reliability, there have been issues with DRI3, but those have been fixed
in X libraries, Mesa, Intel DDX etc.  Mainly you need to use new enough
(full) stack.

Reply at: https://bugs.launchpad.net/ubuntu/+source/xorg-
server/+bug/1440891/comments/15

------------------------------------------------------------------------
On 2016-09-14T10:34:07+00:00 Martin-peres-n wrote:

This bug is also a problem for Wayland. The proper fix is to export a
new property (backlight) attached to the DRM connector object and let
the userspace deal with this. Once this lands, modesetting could be
accessing it.

Now, if older distros require modesetting to work, we would need to port
the workaround found in the intel ddx, but it really is a workaround and
I would rather avoid adding this code in X, so it could live as an
external patch.

Reply at: https://bugs.launchpad.net/ubuntu/+source/xorg-
server/+bug/1440891/comments/16

------------------------------------------------------------------------
On 2016-10-28T17:47:02+00:00 Eugen Dedu wrote:

Hi,

Is there any progress on this bug?  xorg-server 1.19 is being released,
is this bug too risky to fix for the oncoming release?

Reply at: https://bugs.launchpad.net/ubuntu/+source/xorg-
server/+bug/1440891/comments/17

------------------------------------------------------------------------
On 2016-11-02T09:05:26+00:00 Martin-peres-n wrote:

(In reply to Eugen Dedu from comment #11)
> Hi,
> 
> Is there any progress on this bug?  xorg-server 1.19 is being released, is
> this bug too risky to fix for the oncoming release?

We have a patch series on the kernel side that is being polished right
now. This introduces a backlight property on connectors and basically
allow using the KMS interface to control the backlight.

In the coming days, we will start implementing support for it in the
modesetting driver and everything should just work at this point. This
is the cleanest design we could think of even though the kernel side is
way more complex than it used to be.

Do not expect this feature to be ready before Linux 4.11 though :s We
may work on a workaround in the mean time, but I am not sure this will
be worth the effort. Stable distros could backport the patchset if they
care.

Reply at: https://bugs.launchpad.net/ubuntu/+source/xorg-
server/+bug/1440891/comments/18

------------------------------------------------------------------------
On 2017-02-09T18:21:32+00:00 Kloedej wrote:

Thanks for reporting the status.
For me it is somewhat disappointing that a feature like this breaks and stays 
broken for such a long time. If a workaround can be provided to fill the get I 
would very much appreciate it.

Meanwhile, I would just like to add a reference here to the Fedora/RedHat 
bugzilla where some more people have reported probably the same issue:
https://bugzilla.redhat.com/show_bug.cgi?id=1354662

Reply at: https://bugs.launchpad.net/ubuntu/+source/xorg-
server/+bug/1440891/comments/19

------------------------------------------------------------------------
On 2017-02-09T18:22:18+00:00 Kloedej wrote:

sorry, should read "fill the gap:

Reply at: https://bugs.launchpad.net/ubuntu/+source/xorg-
server/+bug/1440891/comments/20

------------------------------------------------------------------------
On 2017-02-10T16:31:46+00:00 Eugen Dedu wrote:

In my case, I was using xbacklight in awesome WM to change screen
backlight.  Noticing that it is not going to be fixed soon, I replaced
xbacklight command with an echo XYZ
>/sys/class/backlight/intel_backlight/brightness, and added a chmod go+w
/sys/class/backlight/intel_backlight/brightness in /etc/rc.local so that
I, as a non-root user, can modify that file.

Reply at: https://bugs.launchpad.net/ubuntu/+source/xorg-
server/+bug/1440891/comments/21

------------------------------------------------------------------------
On 2017-02-10T17:27:27+00:00 Martin-peres-n wrote:

If you(In reply to Jos de Kloe from comment #13)
> Thanks for reporting the status.
> For me it is somewhat disappointing that a feature like this breaks and
> stays broken for such a long time. If a workaround can be provided to fill
> the get I would very much appreciate it.
> 
> Meanwhile, I would just like to add a reference here to the Fedora/RedHat
> bugzilla where some more people have reported probably the same issue:
> https://bugzilla.redhat.com/show_bug.cgi?id=1354662

If you don't mind compiling your own kernel and xserver, I have branches
that work for us. We are in the process of getting everyone to agree on
an ABI for this new KMS property and it won't be easy.

Here are the patches:
 - https://cgit.freedesktop.org/~mperes/linux/log/?h=backlight
 - https://cgit.freedesktop.org/~mperes/xserver/log/?h=backlight

Reply at: https://bugs.launchpad.net/ubuntu/+source/xorg-
server/+bug/1440891/comments/22

------------------------------------------------------------------------
On 2017-03-11T14:49:27+00:00 Yath+fdo-bugzilla wrote:

(In reply to Jos de Kloe from comment #13)
> If a workaround can be provided to fill
> the get I would very much appreciate it.

https://github.com/yath/ybacklight/blob/master/ybacklight

HTH,
 Sebastian

Reply at: https://bugs.launchpad.net/ubuntu/+source/xorg-
server/+bug/1440891/comments/23

------------------------------------------------------------------------
On 2017-03-11T15:10:52+00:00 Eugen Dedu wrote:

You need write access to /sys/class/backlight/*/brightness file, right?  I was 
using:
chmod o+w /sys/class/backlight/intel_backlight/brightness
in my /etc/rc.local file for that.

Reply at: https://bugs.launchpad.net/ubuntu/+source/xorg-
server/+bug/1440891/comments/24

------------------------------------------------------------------------
On 2017-05-02T08:42:27+00:00 Pander wrote:

More people mention that it doesn't work out of the box and that the man
page is not helping them how to get started. Please see
https://bugs.debian.org/cgi-bin/pkgreport.cgi?pkg=xbacklight and
https://bugs.launchpad.net/ubuntu/+source/xbacklight/+bugs?field.status:list=NEW

Perhaps the installer (in e.g. ncurses) should ask if all users should
be allowed to run this or not (default). In this way, the majority of
the users would be able to use this application with more ease.

Reply at: https://bugs.launchpad.net/ubuntu/+source/xorg-
server/+bug/1440891/comments/25

------------------------------------------------------------------------
On 2017-12-21T21:56:37+00:00 Nathan Schulte wrote:

On Debian (Buster), there is a package, brightness-udev, which includes
only the udev scripts of brightnessctl (scripts to allow users of video
group to manage brightness and input group manage leds).

Installing this package avoids the need to modify system files (like
/etc/rc.local noted above).  Also, brightnessctl works to control the
backlight in this case.

Reply at: https://bugs.launchpad.net/ubuntu/+source/xorg-
server/+bug/1440891/comments/26

------------------------------------------------------------------------
On 2018-03-30T12:23:40+00:00 Nico-freedesktop-org wrote:

Fyi - I just wrote cbacklight to cleanly / easily fix this problem:

[14:21] line:~% cbacklight --help
usage: cbacklight [-h] [--inc INC | --dec DEC | --set SET] [--get]

cbacklight

optional arguments:
  -h, --help  show this help message and exit
  --inc INC   Increment by percentage (points)
  --dec DEC   Decrement by percentage (points)
  --set SET   Set to percentage
  --get       Get percentage (default)
[14:21] line:~% cbacklight --inc 5  
[14:21] line:~% cbacklight --dec 5 --get
intel_backlight: 65.19%
[14:22] line:~% 


It was inspired by Sebastian's ybacklight, however it only requires python3 and 
has no external dependencies.

You can find it in the nsbin repository on
https://github.com/telmich/nsbin

Requires you to have sane permissions on the files, but that should be
solved by udev or rc.local

Reply at: https://bugs.launchpad.net/ubuntu/+source/xorg-
server/+bug/1440891/comments/27

------------------------------------------------------------------------
On 2018-12-13T18:10:51+00:00 Gitlab-migration wrote:

-- GitLab Migration Automatic Message --

This bug has been migrated to freedesktop.org's GitLab instance and has
been closed from further activity.

You can subscribe and participate further through the new bug through
this link to our GitLab instance:
https://gitlab.freedesktop.org/xorg/xserver/issues/47.

Reply at: https://bugs.launchpad.net/ubuntu/+source/xorg-
server/+bug/1440891/comments/28


** Changed in: xorg-server
       Status: Confirmed => Unknown

** Bug watch added: Red Hat Bugzilla #1354662
   https://bugzilla.redhat.com/show_bug.cgi?id=1354662

-- 
You received this bug notification because you are a member of Ubuntu-X,
which is subscribed to xorg-server in Ubuntu.
https://bugs.launchpad.net/bugs/1440891

Title:
  xbacklight doesn'twork with modesetting driver

To manage notifications about this bug go to:
https://bugs.launchpad.net/xorg-server/+bug/1440891/+subscriptions

_______________________________________________
Mailing list: https://launchpad.net/~ubuntu-x-swat
Post to     : ubuntu-x-swat@lists.launchpad.net
Unsubscribe : https://launchpad.net/~ubuntu-x-swat
More help   : https://help.launchpad.net/ListHelp

Reply via email to