[Bug 96996] [BYT][VLV] No picture on DSI display after DRM loads on Teclast X80H tablet

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=96996

--- Comment #18 from Stephan Schorn <mail at schorn-stephan.de> ---
Created attachment 129075
  --> https://bugs.freedesktop.org/attachment.cgi?id=129075&action=edit
dmesg of 4.10.0-rc3 drm-tip with i915.fastboot=1 (forced to work by dirty
patch), DSI screen works

I got it working!

At least with a very dirty patch:

In intel_display.c, I changed the line


FROM

if (i915.fastboot && intel_pipe_config_compare(dev,
to_intel_crtc_state(crtc->state), pipe_config, true)) {

TO

if (i915.fastboot) {


That way, fastboot can be enabled by kernel parameter i915.fastboot=1 again.

Although, if you only add this kernel parameter, the system won't boot, it will
hang. I don't know why.
You have to remove quiet and splash (or only one of them, I don't know).
Then, the system will boot absolutely normal.

Acceleration works, rotating the screen works etc.

The other problems like the real time clock bug and system freezes persist, but
you'll get a working system - for a few minutes.

I don't have time to further investigate this stuff this evening, but I hope
you'll be happy to know that the screen can be made working!

You'll find the dmesg of my successful boot as attachment.

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