<html> <head> <base href="https://bugs.freedesktop.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW - i915: intel_dp_aux_backlight max_brightness set to incorrect value on Thinkpad P1 Gen2 AMOLED" href="https://bugs.freedesktop.org/show_bug.cgi?id=112014#c7">Comment # 7</a> on <a class="bz_bug_link bz_status_NEW " title="NEW - i915: intel_dp_aux_backlight max_brightness set to incorrect value on Thinkpad P1 Gen2 AMOLED" href="https://bugs.freedesktop.org/show_bug.cgi?id=112014">bug 112014</a> from <a class="email" href="mailto:lyude@redhat.com" title="Lyude Paul <lyude@redhat.com>"> Lyude Paul</a> <pre>Hi! Jani Nakula pointed me towards this when I started asking around about the AMOLED backlight issues I'm seeing on an X1 Extreme 2nd Gen laptop that I got for testing purposes. While the patch that they linked here isn't enough, I've done a bit of experimenting and I managed to hack together something that actually works on my X1 extreme 2nd gen. There seem to be three different underlying issues here: - The first, as the reporter here pointed out, is that we're not setting the max/min backlight correctly - The second is that i915 with these patches appears to program DP_EDP_PWMGEN_BIT_COUNT at the start of the driver load, but never again. This doesn't seem to be correct since the panel forgets this value once it's been switched into D3 mode, so it needs to be programmed when enabling the backlight after the panel was previously shut off as well - The third is that there appears to be a mandatory delay time that occurs after the initial link training process, before we're able to properly program the backlight registers over DPCD. Not sure what this is (msleep(500) seems to work..l.), but I'm assuming it's probably the same as the normal panel power cycle delays. I'll try writing up some patches for this in a short bit and link to them here</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>