<html> <head> <base href="https://bugs.freedesktop.org/" /> </head> <body> <div> <a class="bz_bug_link bz_status_NEEDINFO " title="NEEDINFO --- - Backlight control broken on Dell XPS13 w/ kernel 3.14-rc7" href="https://bugs.freedesktop.org/show_bug.cgi?id=76276#c18">Comment # 18</a> on <a class="bz_bug_link bz_status_NEEDINFO " title="NEEDINFO --- - Backlight control broken on Dell XPS13 w/ kernel 3.14-rc7" href="https://bugs.freedesktop.org/show_bug.cgi?id=76276">bug 76276</a> from <a class="email" href="mailto:bugs@mrvanes.com" title="Martin <bugs@mrvanes.com>"> Martin</a> <pre>Created <a href="attachment.cgi?id=97111" name="attach_97111" title="As requested">attachment 97111</a> <a href="attachment.cgi?id=97111&action=edit" title="As requested">[details]</a> As requested Some answers and output: Let me start by saying that the backlight is ON, so I can work. The only thing that stopped working is backlight control in KDE powercontrol interface. 1. Does acpi_backlight work after that? The KDE powercontrol interface works again after that (my main concern). Echo'ing values between 0 and 100 in /sys/class/backlight/acpi_video0/brightness correctly sets the brightness. Echoing values between 0 and /sys/class/backlight/intel_backlight/max_brightness to /sys/class/backlight/intel_backlight/brightness makes the backlight pulsate (slowly) except for max_brightness which makes the backlight max without pulse. acpi_video0 doesn't work then. 2. Please attach /sys/kernel/debug/dri/0/i915_opregion See attached file. 3. Also please provide a reg dump *before* i915 gets loaded. Does acpi_backlight work before i915 is loaded? I think this is one of the things I can't easily help you with, i915 is compiled into my kernel since it makes no sense booting without (to me). 4. Also, is there a difference between EFI vs. legacy boot? I boot legacy and have no EFI partition. I don't want to risk reformatting my drive, since this is my daily workhorse. 5. Please do all of the above, and additionally try this hack Done. This fixes my problem.</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the QA Contact for the bug.</li> <li>You are on the CC list for the bug.</li> </ul> </body> </html>