<html> <head> <base href="https://bugs.freedesktop.org/" /> </head> <body> <div> <a class="bz_bug_link bz_status_NEEDINFO " title="NEEDINFO - screen brightness regression on resume" href="https://bugs.freedesktop.org/show_bug.cgi?id=88325#c9">Comment # 9</a> on <a class="bz_bug_link bz_status_NEEDINFO " title="NEEDINFO - screen brightness regression on resume" href="https://bugs.freedesktop.org/show_bug.cgi?id=88325">bug 88325</a> from <a class="email" href="mailto:dantti12@gmail.com" title="Daniel Nicoletti <dantti12@gmail.com>"> Daniel Nicoletti</a> <pre>This is the commit which introduced the regression, by the description it seems to be it: daniel@bart:~/code/drm-intel$ git bisect good c675949ec58ca50d5a3ae3c757892f1560f6e896 is the first bad commit commit c675949ec58ca50d5a3ae3c757892f1560f6e896 Author: Jani Nikula <<a href="mailto:jani.nikula@intel.com">jani.nikula@intel.com</a>> Date: Wed Apr 9 11:31:37 2014 +0300 drm/i915: do not setup backlight if not available according to VBT Some machines use an external EC for controlling the backlight. Info about this is present in the VBT. Do not setup native backlight control if no PWM backlight is available or supported according to VBT. The acpi_backlight interface appears to work for the EC control. In most cases there has been no harm done, but it looks like there are machines out there that have both an EC and our PWM line connected to the same wire. This, obviously, does not end well. This should fix the regression caused by commit bc0bb9fd1c7810407ab810d204bbaecb255fddde Author: Jani Nikula <<a href="mailto:jani.nikula@intel.com">jani.nikula@intel.com</a>> Date: Thu Nov 14 12:14:29 2013 +0200 drm/i915: remove QUIRK_NO_PCH_PWM_ENABLE AFAICT the quirk removed by the above commit effectively resulted in i915 not driving the backlight PWM output, thus not messing things up. Additionally this should fix the regression caused by commit fbc9fe1b4f222a7c575e3bd8e9defe59c6190a04 Author: Aaron Lu <<a href="mailto:aaron.lu@intel.com">aaron.lu@intel.com</a>> Date: Fri Oct 11 21:27:45 2013 +0800 ACPI / video: Do not register backlight if win8 and native interface exists which left some machines without a functioning backlight interface. Bugzilla: <a class="bz_bug_link bz_status_RESOLVED bz_closed" title="RESOLVED FIXED - Backlight control broken on Dell XPS13 w/ kernel 3.14-rc7" href="show_bug.cgi?id=76276">https://bugs.freedesktop.org/show_bug.cgi?id=76276</a> Reference: <a href="https://bugzilla.kernel.org/show_bug.cgi?id=47941">https://bugzilla.kernel.org/show_bug.cgi?id=47941</a> Bugzilla: <a href="https://bugzilla.kernel.org/show_bug.cgi?id=62281">https://bugzilla.kernel.org/show_bug.cgi?id=62281</a> CC: Aaron Lu <<a href="mailto:aaron.lu@intel.com">aaron.lu@intel.com</a>> CC: Eric Griffith <<a href="mailto:EGriffith92@gmail.com">EGriffith92@gmail.com</a>> CC: Kent Baxley <<a href="mailto:kent.baxley@canonical.com">kent.baxley@canonical.com</a>> Tested-by: Kamal Mostafa <<a href="mailto:kamal@canonical.com">kamal@canonical.com</a>> Tested-by: Martin <<a href="mailto:bugs@mrvanes.com">bugs@mrvanes.com</a>> Tested-by: <a href="mailto:jrg.otte@gmail.com">jrg.otte@gmail.com</a> Reviewed-by: Ville Syrjälä <<a href="mailto:ville.syrjala@linux.intel.com">ville.syrjala@linux.intel.com</a>> Signed-off-by: Jani Nikula <<a href="mailto:jani.nikula@intel.com">jani.nikula@intel.com</a>> :040000 040000 9ed3e48521f181c53dfe780b28450e678aa4b9ea b9a776bb2de3ba84f614087619e9e91a2bdcc960 M drivers</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> <li>You are the assignee for the bug.</li> </ul> </body> </html>