Dear Maintainer,
I was running a Jessie system until this morning, now I dist-upgraded to Stretch and I have a problem which looks related to the intel driver.
I'm on an old Acer laptop, and before the upgrade the backlight controls worked fine passing acpi_backlight=vendor and acpi_osi=Linux on the kernel command line.
Now it doesn't work anymore, I can adjust backlight echoing a value in /sys/class/backlight/intel_backlight/backlight but nor hotkeys neither applets can adjust it.
After some googling I tried creating a configuration file in /etc/X11/xorg.conf.d, to tell it to use intel_backlight instead of acer-wmi, but it still doesn't work.
I saw that in /usr/X11/xorg.conf.d there is a file to tell the driver to use UXA acceleration, but reading Xorg.log looks like SNA is used instead.
Also in Xorg.log it tells it's loading the platform driver, which has never worked AFAIK, so I guess the problem is just that every option passed to the driver is simply ignored.
Tried even adding video.use_native_backlight=1 on kernel command line with no luck.

Kind regards
Massimo

*** Reporter, please consider answering these questions, where appropriate ***

   * What led up to the situation?
   * What exactly did you do (or not do) that was effective (or
     ineffective)?
   * What was the outcome of this action?
   * What outcome did you expect instead?

*** End of the template - remove these template lines ***

Actually I found that the other files in /usr/X11/xorg.conf.d containing
a section "Device" were not shipped with any package, so I merged all
options in a single file in /etc/X11/xorg.conf.d with also a "Screen"
section. Here is its content:

===========================================
Section "Screen"
        Identifier "Laptop Screen"
        Device "Intel Graphics"
        Monitor "LVDS Monitor"
EndSection

Section "Monitor"
        Identifier "LVDS Monitor"
        Gamma 0.70 0.72 0.68
EndSection

Section "Device"
        Identifier "Intel Graphics"
        Driver "intel"
#       Option "AccelMethod" "uxa"
        Option "Backlight" "intel_backlight"
        Option "monitor-LVDS1" "LVDS Monitor"
        BusID "PCI:0:2:0"
EndSection
===========================================

Now the driver correctly uses the intel_backlight interface and I'm able
to adjust backlight again, so the bug is now just that it just ignores
options on the kernel command line, while on Jessie the same options are
taken into account.

Kind regards
Massimo Maiurana

Please report kernel issues against the kernel.  As for configuration of
the X driver, sharing your actual config would help.

Cheers,
Julien

Julien Cristau ha scritto il 23/06/2015 alle 21:12:

What config do you need? I don't have any config not listed above,
unless I'm missing something obvious and in that case, please, tell what
can I provide.

I'll report this issue even against the kernel, thanks.

Massimo Maiurana