[i915 KMS] No screen image after modeset on Intel Atom x5-Z8300

Submitted by zvezdin

Assigned to Intel GFX Bugs mailing list

Link to original bug (#109760)

Description

Created attachment 143448
Dmesg on a boot demonstrating the issue

Bug description:


I've got an Acer Switch 10e SW3-016 tablet (Intel Atom x5-Z8300) and have been fighting in getting a working Linux environment on it for the last couple of months.

Most notably, booting any distro displays the kernel log until KMS loads Intel drivers, after which the screen briefly flashes white and stops displaying an image. I can ssh, successfully start and interact with X, change brightness levels (and since it's an LCD display I can see brightness changes), just that all I see is black pixels.

Kernel parameter i915.fastboot=1 temporarily fixes this issue - the display works, until the screen is shut off (to either sleep or manually "xset dpms force off"). After the screen wakes up, there is again no screen image (brightness and everything else works as normal).

I tried manually compiling and installing the recommended drm-tip, but the issue stays the same.

I've attached the full dmesg (with drm.debug=0x1e log_buf_len=1M kernel params), and an intel_reg dump.
I couldn't dump the VBIOS:
cat: /sys/devices/pci0000:00/0000:00:02.0/rom: Input/output error

System environment:
-- chipset:
-- system architecture: 64-bit
-- xf86-video-intel: N/A
-- xserver: N/A
-- mesa: N/A
-- libdrm: 2.4.97
-- kernel: 4.20.11-arch2-1-ARCH
-- Linux distribution: Arch
-- Machine or mobo model: Acer Switch SW3-016
-- Display connector: DSI

Reproducing steps:

Additional info:

Attachment 143448, "Dmesg on a boot demonstrating the issue":
dmesg-drm.debug_0x1e-log_buf_len_1M.txt