I did some more testing and I nailed the change to the 3.15.7 kernel update. I must have confused versions in my initial report.
Anyways, looking throught the changelog for that kernel version I found this changeset : commit be907c8468c9f47882036109ba550cd2748b86a0 Author: Alex Deucher <[email protected]> Date: Tue Jul 15 09:48:53 2014 -0400 drm/radeon: set default bl level to something reasonable commit 201bb62402e0227375c655446ea04fcd0acf7287 upstream. If the value in the scratch register is 0, set it to the max level. This fixes an issue where the console fb blanking code calls back into the backlight driver on unblank and then sets the backlight level to 0 after the driver has already set the mode and enabled the backlight. bugs: https://bugs.freedesktop.org/show_bug.cgi?id=81382 https://bugs.freedesktop.org/show_bug.cgi?id=70207 Signed-off-by: Alex Deucher <[email protected]> Tested-by: David Heidelberger <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> This modified the way the radeon module handles default backlight values. Looking through the first bug report I found out about the "radeon.backlight" kernel option. Adding "radeon.backlight=0" to grub command line fixed the display brightness issue. ** Bug watch added: freedesktop.org Bugzilla #81382 https://bugs.freedesktop.org/show_bug.cgi?id=81382 ** Bug watch added: freedesktop.org Bugzilla #70207 https://bugs.freedesktop.org/show_bug.cgi?id=70207 ** Also affects: xserver-xorg-driver-radeonhd via https://bugs.freedesktop.org/show_bug.cgi?id=81382 Importance: Unknown Status: Unknown -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1363623 Title: [ASUS-A7K laptop] screen brightness dimmed after kernel update To manage notifications about this bug go to: https://bugs.launchpad.net/xserver-xorg-driver-radeonhd/+bug/1363623/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
