<html> <head> <base href="https://bugs.freedesktop.org/" /> </head> <body> <div> <a class="bz_bug_link bz_status_RESOLVED bz_closed" title="RESOLVED FIXED - [i915 intel_backlight] can't regulate brightness at GDM login prompt if HDMI monitor connected" href="https://bugs.freedesktop.org/show_bug.cgi?id=87286#c21">Comment # 21</a> on <a class="bz_bug_link bz_status_RESOLVED bz_closed" title="RESOLVED FIXED - [i915 intel_backlight] can't regulate brightness at GDM login prompt if HDMI monitor connected" href="https://bugs.freedesktop.org/show_bug.cgi?id=87286">bug 87286</a> from <a class="email" href="mailto:luca.boccassi@gmail.com" title="Luca Boccassi <luca.boccassi@gmail.com>"> Luca Boccassi</a> <pre>(In reply to Aaron Lu from <a href="show_bug.cgi?id=87286#c20">comment #20</a>) > (In reply to Luca Boccassi from <a href="show_bug.cgi?id=87286#c19">comment #19</a>) > > Hello Aaron, > > > > That package ships a binary, xf86-video-intel-backlight-helper, which > > apparently is used to regulate the brightness. I'm not familiar with the > > code myself or the project itself, but with a quick Google search this Xorg > > mailer thread came up and it does shed some light on how this is used: > > <a href="http://lists.x.org/archives/xorg-devel/2014-February/040575.html">http://lists.x.org/archives/xorg-devel/2014-February/040575.html</a> > > Thanks for the pointer. The helper is used to write a value to the > /sys/class/backlight/X/brightness and the fact that it now works means that > the native interface works and the original problem may be due to broken > user space tool. You can verify by doing this(when the native interface is > still there): > # cd /sys/class/backlight/intel_backlight > # cat max_brightness > XXX > # echo some_value_less_than_max > brightness > See if backlight level changes. Of source you will also need to verify if > the interface still works after hotplug as your original scenario. > > If the backlight indeed works, then we have mistakenly disabled the native > interface and I think we should revert that patch. Hello Aaron, I just tested and it works as expected, brightness changes. Tested on Jessie with both 3.18 and 3.19, and the 2.99.917-1 xserver-xorg-video-intel. But please note that, although I believe the problem is the same since the GPU family and drivers are the same, I have a different laptop: Dell Latitude E5540, running an Intel Haswell i7-4600U with GPU HD Graphics 4400. So we should have someone with the Samsung laptop (which has an HD4000 I think) to confirm as well, to be sure. Kind regards, Luca Boccassi</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>