<html> <head> <base href="https://bugs.freedesktop.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_NEEDINFO " title="NEEDINFO - i915.fastboot=1 is broken on Thinkpad S1 Yoga (Haswell)" href="https://bugs.freedesktop.org/show_bug.cgi?id=108773#c19">Comment # 19</a> on <a class="bz_bug_link bz_status_NEEDINFO " title="NEEDINFO - i915.fastboot=1 is broken on Thinkpad S1 Yoga (Haswell)" href="https://bugs.freedesktop.org/show_bug.cgi?id=108773">bug 108773</a> from <a class="email" href="mailto:ville.syrjala@linux.intel.com" title="Ville Syrjala <ville.syrjala@linux.intel.com>"> Ville Syrjala</a> <pre>(In reply to Johannes Krampf from <a href="show_bug.cgi?id=108773#c18">comment #18</a>) > Created <a href="attachment.cgi?id=144329" name="attach_144329" title="Dmesg of drm-tip with fastboot on T440s">attachment 144329</a> <a href="attachment.cgi?id=144329&action=edit" title="Dmesg of drm-tip with fastboot on T440s">[details]</a> > Dmesg of drm-tip with fastboot on T440s > > This is drm-tip version 307cedb7b907ee533bf9e746d0e06bea04f2722b from Thu > May 23 12:49:55 2019 +1000. I used drm.debug=0xe on the kernel flags as > requested. Previously I had 0x1e. > > The behaviour changed slightly with drm-tip: > > On startup, I still get the sub-second flash with boot messages and then the > screen _including the backlight_ turns off. I can interact with the system > (wayland+VT), but get no screen output. OK. I guess we're dealing with a backlight problem at this point. We do see the telltale signs here: [ 0.910355] [drm:lpt_setup_backlight] CPU backlight register was enabled, switching to PCH override The code was supposed to be fixed so that it can do the CPU->PCH switch but it looks like it's still not working correctly.</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are on the CC list for the bug.</li> <li>You are the QA Contact for the bug.</li> <li>You are the assignee for the bug.</li> </ul> </body> </html>