[Intel-gfx] Baytrail MIPI/DSI Black when boot with HDMI connected

[Jani Nikula]

On Fri, 28 Oct 2016, Fabian Pie <fpie at teleker.com> wrote:
> Hi,
> I'm testing Baytrail device with mipi/dsi display and hdmi output. When I
> boot without the hdmi connected the mipi/dsi works OK and after connecting
> the hdmi both mipi/dsi and hdmi display graphics OK.
> If I boot with the hdmi connected it's selected by the bios as the default
> display, Ubuntu only boots in hdmi and it works OK in this display but
> MIPI/DSI is black. It's listed as connected by xrandr but I can't reset in
> any way.
> I didn't find this issue in your bug list. Have you seen anything similar ?
> I'm using Ubuntu 16.10 with kernel 4.8.4

Probably the BIOS skips some DSI initialization in this case, and we
fail to bring it up. Please file a bug over at [1], include the above
description, add drm.debug=14 module parameter, attach dmesg all the way
from boot for both the working and broken cases, plus
/sys/kernel/debug/dri/0/i915_vbt.

BR,
Jani.

[1] https://bugs.freedesktop.org/enter_bug.cgi?product=DRI&component=DRM/Intel



-- 
Jani Nikula, Intel Open Source Technology Center