I booted with drm.debug=14 and looked at the output of dmesg. It had lines like [ 0.717202] [drm:i915_dump_device_info] i915 device info: gen=7, pciid=0x0412 rev=0x06 flags=need_gfx_hws,is_haswell,has_fbc,has_hotplug,has_llc,has_ddi,has_fpga_dbg, ... [ 0.938640] [drm:drm_helper_probe_single_connector_modes_merge_bits] [CONNECTOR:36:VGA-1] disconnected [ 0.938641] [drm:drm_helper_probe_single_connector_modes_merge_bits] [CONNECTOR:39:HDMI-A-1] [ 0.938642] [drm:intel_hdmi_detect] [CONNECTOR:39:HDMI-A-1]
which made me realize: the drm driver cares a lot about which video connector you plug into. On a whim, I replaced the DVI video cable with a VGA one... and the problem went away! So, that's a better workaround for me: just use a vga cable. ** Summary changed: - black screen at boot until pressing power-off button? + haswell i915 black screen regression with DVI; VGA ok? -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xserver-xorg-video-intel in Ubuntu. https://bugs.launchpad.net/bugs/1639640 Title: haswell i915 black screen regression with DVI; VGA ok? To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/1639640/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp
