I have this problem with i915. When the kernel is loading the modules, when i915 is loaded, if the HDMI cable is connected the video on the LVDS connected LCD looks distorted. I'm using a brand-less AIO computer that uses a Pegatron Thin-mini ITX motherboard. If I connect the HDMI cable after i915 has loaded then no problems (video works on LCD and HDMI external monitor). If booting with HDMI cable attached, video only displays on the external monitor while on BIOS, and when the i915 loads the LCD goes ON but image looks distorted. This happens on more than one of these computers (I have several, they all have this problem). Tried kernels 3.12.33 and 3.18. Same problem on both.
Created attachment 162781 [details] dmesg output with hdmi from power up this is the dmesg output with the HDMI external monitor attached from power up. The video looks distorted once the i915 is loaded.
Created attachment 162791 [details] dmesg output if HDMI connected after i915 loads dmesg output if cable is connected right after i915 is loaded.
Please try a more recent kernel, preferrably v3.19. If the problem persists with a new kernel, please attach intel_reg_dumper output both for the distorted and non-distorted cases. intel_reg_dumper is part of intel-gpu-tools http://cgit.freedesktop.org/drm-intel. Also the dmesg for the new kernel might be useful, with drm.debug=14 module parameter.
Long time no updates, closing. If the problem persists with latest kernels, please file a bug at the freedesktop.org bugzilla [1], referencing this bug. Thank you. [1] https://bugs.freedesktop.org/enter_bug.cgi?product=DRI&component=DRM/Intel