Bug 93799

Summary: [BYT] Blank screen on DSI display after drm loads on Teclast X80h tablet
Product: DRI Reporter: Laszlo Fiat <laszlo.fiat>
Component: DRM/IntelAssignee: Intel GFX Bugs mailing list <intel-gfx-bugs>
Status: CLOSED DUPLICATE QA Contact: Intel GFX Bugs mailing list <intel-gfx-bugs>
Severity: normal    
Priority: medium CC: intel-gfx-bugs, laszlo.fiat
Version: unspecified   
Hardware: x86-64 (AMD64)   
OS: Linux (All)   
Whiteboard:
i915 platform: BYT i915 features: display/DSI
Attachments:
Description Flags
dmesg of the kernel where screen is working
none
dmesg of the kernel where screen does not work
none
xrandr verbose output when screen is working
none
kernel config of the working kernel
none
kernel config where the screen does not work
none
dmesg of kernel compiled from drm-intel-nightly, built-in display doesn't work none

Description Laszlo Fiat 2016-01-20 18:22:46 UTC 
I can see the boot logo, the grub menu, and first few lines as the kernel loads, then the built-in screen of the tablet goes blank. Backlight is still on, but nothing is on the display.

Steps to reproduce the issue: Boot up the tablet without HDMI connected.
How often does the steps listed above trigger the issue: Always
system architecture: x86_64
kernel version: 4.4.0-rc2-next-20151127+
Linux distribution: Debian Testing
Machine or mother board model: Teclast X80h Baytrail tablet
Display connector: DSI (built-in display)

I have one kernel version (4.3.0-rc5-next-20151012+), which actually works correctly, none of the earlier or later versions I tried works.

I attach the dmesg for both working and non-working kernels.
I can provide more information if needed.
Comment 1 Laszlo Fiat 2016-01-20 18:24:30 UTC 
Created attachment 121156 [details]
dmesg of the kernel where screen is working
Comment 2 Laszlo Fiat 2016-01-20 18:26:23 UTC 
Created attachment 121157 [details]
dmesg of the kernel where screen does not work
Comment 3 Laszlo Fiat 2016-01-20 18:29:03 UTC 
Created attachment 121159 [details]
xrandr verbose output when screen is working
Comment 4 Laszlo Fiat 2016-01-20 18:34:54 UTC 
Created attachment 121160 [details]
kernel config of the working kernel
Comment 5 Laszlo Fiat 2016-01-20 18:37:13 UTC 
Created attachment 121161 [details]
kernel config where the screen does not work
Comment 6 Jani Nikula 2016-01-21 09:35:37 UTC 
Please try drm-intel-nightly branch of http://cgit.freedesktop.org/drm-intel
Comment 7 Laszlo Fiat 2016-01-24 17:58:32 UTC 
Created attachment 121245 [details]
dmesg of kernel compiled from drm-intel-nightly, built-in display doesn't work

I have compiled from intel-nightly-branch as instructed. The built-in display goes blank after drm loads. There is a WARNING in dmesg in all kernels, where the display goes blank, this one is from the dmesg of intel-nightly-branch:

[    6.664456] WARNING: CPU: 3 PID: 58 at drivers/gpu/drm/drm_irq.c:1271 drm_wait_one_vblank+0x13b/0x180 [drm]()
[    6.664457] vblank wait timed out on crtc 0

The full dmesg is attached.

Please note that I have a kernel version (linux-next-20151012) where the screen works correctly, you can find the dmesg as the first attachment for this bug, if you wish to compare it.
Comment 8 Laszlo Fiat 2016-01-24 18:02:28 UTC 
Tried drm-intel-nightly as instructed. Further information provided.
Comment 9 Laszlo Fiat 2016-05-16 10:17:53 UTC 
As I wrote at bug 90469, adding i915.fastboot=1 to the kernel command line enables the DSI display. See the details at bug 90469.
Comment 10 Laszlo Fiat 2016-05-16 10:18:53 UTC 

*** This bug has been marked as a duplicate of bug 90469 ***

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