just to inform that i opened 2 bug report
one on kernel.org and an other on Xorg
here is the link of the last one
http://bugs.freedesktop.org/show_bug.cgi?id=18590
because with acpi=off it worked, i opened first an acpi bug, but in console mode (CTRL ALT F1 for example) the brightness work well, i was told it is no acpi bug and i needed to open an Xorg bug.
just to inform that i opened 2 bug report
one on kernel.org
and an other on Xorg
here is the link of the last one
http:// bugs.freedeskto p.org/show_ bug.cgi? id=18590
because with acpi=off it worked, i opened first an acpi bug, but in console mode (CTRL ALT F1 for example) the brightness work well, i was told it is no acpi bug and i needed to open an Xorg bug.