[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 #16 from Laszlo Fiat <laszlo.fiat at gmail.com> ---
@Stephan Schorn 

Thank you for looking into this. 

CDCLK can be easily set in intel_display.c, in valleyview_calc_cdclk routine.
I have tried to fix it to 333333 KHz, but it wasn't enough to get the DSI
screen working.

I think GMBUS is only related to HDMI/DP, and those are not connected, that is
why the error in the dmesgs.

I also tried to fix the dsi pll div to the correct value (18d) shown by the
intel_reg with fastboot=1, but still no picture.

What I try to do is to compile the "ancient" android-ia kernel for
Baytrail/Cherryview, it is based on vanilla 3.14.64, plus a quilt (bunch of
patches) from
https://github.com/01org/ProductionKernelQuilts/blob/master/README.md . This
patchset contains everything that is needed to run android on
Baytrail/Cherryview. It contains lots of code that never got mainlined (e.g.
proper power management ic support). We also need the EFI_MIXED patchset that
went into 3.15, because we want a 64 bit kernel that boots on our 32 bit EFI
(http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=7cc3afdf43ffb703db831292f3816d909fd44767
). And also a nice .config file (enabling lots of options that the patches
bring in).

I want to try this kernel to see if it can initialize our display.

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