[Bug 109760] New: [i915 KMS] No screen image after modeset on Intel Atom x5-Z8300

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=109760

            Bug ID: 109760
           Summary: [i915 KMS] No screen image after modeset on Intel Atom
                    x5-Z8300
           Product: DRI
           Version: unspecified
          Hardware: x86-64 (AMD64)
                OS: Linux (All)
            Status: NEW
          Severity: major
          Priority: medium
         Component: DRM/Intel
          Assignee: intel-gfx-bugs at lists.freedesktop.org
          Reporter: git at zvezd.in
        QA Contact: intel-gfx-bugs at lists.freedesktop.org
                CC: intel-gfx-bugs at lists.freedesktop.org

Created attachment 143448
  --> https://bugs.freedesktop.org/attachment.cgi?id=143448&action=edit
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:

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