<html> <head> <base href="https://bugs.freedesktop.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW - Brightness control inversion from VBT table is not taken into account in Ubuntu 18.10" href="https://bugs.freedesktop.org/show_bug.cgi?id=111475#c10">Comment # 10</a> on <a class="bz_bug_link bz_status_NEW " title="NEW - Brightness control inversion from VBT table is not taken into account in Ubuntu 18.10" href="https://bugs.freedesktop.org/show_bug.cgi?id=111475">bug 111475</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 Szymon from <a href="show_bug.cgi?id=111475#c5">comment #5</a>) > 2. Once BIOS writes 0xC8250 MMIO register with bit 29, backlight logic is > inverted correctly. However 10% minimum brightness level defined in VBT > table is NOT taken into account in this case, i.e. Linux brightness slider > set at maximum produces complete darkness instead of 10% brightness (as set > as minimum). > > 3. In comparison to point 2: Once backlight logic is inverted by kernel boot > parameter acpi_backlight=vendor i915.invert_brightness=1, slider at max > still respects minimum brightness level 10% defined in VBT. Err, what? Slider set at max should produce max brightness instead of darkness, right? Slider set at min should produce min brightness. I'm at a loss with what you're trying to accomplish. Perhaps we should take the GUI sliders out of the equation, and use /sys/class/backlight/intel_backlight/ directly. This should set the backlight to minimum brightness: # echo 0 > brightness This should set the backlight to maximum brightness: # echo $(cat max_brightness) > brightness</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>