<html> <head> <base href="https://bugs.freedesktop.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_NEEDINFO " title="NEEDINFO - Acer V3-772G screen brightness cannot be adjusted with i915.fastboot enabled" href="https://bugs.freedesktop.org/show_bug.cgi?id=108225#c12">Comment # 12</a> on <a class="bz_bug_link bz_status_NEEDINFO " title="NEEDINFO - Acer V3-772G screen brightness cannot be adjusted with i915.fastboot enabled" href="https://bugs.freedesktop.org/show_bug.cgi?id=108225">bug 108225</a> from <a class="email" href="mailto:jani.nikula@intel.com" title="Jani Nikula <jani.nikula@intel.com>"> Jani Nikula</a> <pre>(In reply to Basil Eric Rabi from <a href="show_bug.cgi?id=108225#c11">comment #11</a>) > How can I do a modeset? Try 'xrandr --output eDP-1 --off --output eDP-1 --auto' If that helps when the bug is on, it would really be helpful if you could provide the output of the following 1) after boot, 2) after running the above. # intel_reg read 0xc8250 0xc2004 0xc8254 0x61250 0x61254 intel_reg is a tool in the intel-gpu-tools, or IGT. I suspect the BIOS or GOP sets up different backlight settings from what i915 does, and after fastboot the backlight adjustment writes have no effect. (Note to my future self and other developers: My hunch says GOP does not set BLM_PCH_OVERRIDE_ENABLE and uses the CPU register to adjust backlight, while i915 uses PCH override and uses the PCH register to adjust backlight. Without the override, the PCH register does not have effect. PCH override is the default after Lynxpoint, so we use that mode also for LPT.)</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the assignee for the bug.</li> <li>You are the QA Contact for the bug.</li> <li>You are on the CC list for the bug.</li> </ul> </body> </html>