[Bug 92866] New: "vbetool dpms on" doesn't work with i915 Haswell

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=92866

            Bug ID: 92866
           Summary: "vbetool dpms on" doesn't work with i915 Haswell
           Product: DRI
           Version: unspecified
          Hardware: x86 (IA32)
                OS: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: DRM/Intel
          Assignee: intel-gfx-bugs at lists.freedesktop.org
          Reporter: holgerschurig at gmail.com
        QA Contact: intel-gfx-bugs at lists.freedesktop.org
                CC: intel-gfx-bugs at lists.freedesktop.org

This bug is about the kernel module i915 in text (framebuffer) mode. It's not
about any X11 driver. So I hope the Component is right.

I tested it with Linux 3.18.24 and 4.3.

What I want to achive: I want to turn off the backlight. On some other i915
based hardware (8086:a011) this worked with "vbetool dpms on" and back on with
"vbetool dpms off".

With my i915/Haswell (8086:0a16) the "turn off" part works, albeit I get error
messages in dmesg. But the "turn on" doesn't work: Backlight goes on, but LCD
display stays black.


root:/sys# dmesg -c >/dev/null
root:/sys# vbetool dpms off
root:/sys# dmesg -c
[  325.704229] [drm:intel_uncore_check_errors [i915]] *ERROR* Unclaimed
register before interrupt
[  326.290205] [drm:intel_uncore_check_errors [i915]] *ERROR* Unclaimed
register before interrupt
root:/sys# vbetool dpms on
root:/sys# dmesg -c
[  340.408883] [drm:intel_uncore_check_errors [i915]] *ERROR* Unclaimed
register before interrupt
[  340.682288] [drm:intel_set_cpu_fifo_underrun_reporting [i915]] *ERROR*
uncleared fifo underrun on pipe A
[  340.682348] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU
pipe A FIFO underrun

When I run "vbetool vbestate save" I also get a number of error messages, as
well as with "vbetool vbestate restore". It however restores the display
partially: But it's greatly enlarged, probably the upper
left quarter of the former display now magnified over the whole screen.


Some dmesg output related to the i915/Haswell:

[    0.221025] vgaarb: setting as boot device: PCI:0000:00:02.0
[    0.221099] vgaarb: device added:
PCI:0000:00:02.0,decodes=io+mem,owns=io+mem,locks=none
[    0.221168] vgaarb: loaded
[    0.221225] vgaarb: bridge control possible 0000:00:02.0
...
[    2.969865] [drm] Memory usable by graphics device = 2048M
[    2.969930] [drm] Replacing VGA console driver
[    2.970595] Console: switching to colour dummy device 80x25
[    2.976807] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[    2.976814] [drm] Driver supports precise vblank timestamp query.
[    2.976895] vgaarb: device changed decodes:
PCI:0000:00:02.0,olddecodes=io+mem,decodes=io+mem:owns=io+mem
[    3.003257] fbcon: inteldrmfb (fb0) is primary device
[    3.005096] ACPI: Video Device [GFX0] (multi-head: yes  rom: no  post:
no)
[    3.005312] input: Video Bus as
/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/LNXVIDEO:00/input/input17
[    3.005362] [drm] Initialized i915 1.6.0 20150731 for 0000:00:02.0 on
minor 0
[    4.092573] Console: switching to colour frame buffer device 128x48
[    4.096012] i915 0000:00:02.0: fb0: inteldrmfb frame buffer device
...


vbetool is 1.1

If there is something else beside vbetool I would use it. The files in
/sys/class/backlight/intel_backlight/* seem to be no-op on my board.
One thing: after running "vbotool dpms off", the file dpms in
/sys/class/drm/card0-DP-2/ stays in state "On". But it's the only connected
port:

root at hwtester:~# grep -d skip . /sys/class/drm/*/enabled
/sys/class/drm/card0-DP-1/enabled:disabled
/sys/class/drm/card0-DP-2/enabled:enabled
/sys/class/drm/card0-HDMI-A-1/enabled:disabled
/sys/class/drm/card0-HDMI-A-2/enabled:disabled
root at hwtester:~# grep -d skip . /sys/class/drm/*/dpms
/sys/class/drm/card0-DP-1/dpms:Off
/sys/class/drm/card0-DP-2/dpms:On
/sys/class/drm/card0-HDMI-A-1/dpms:Off
/sys/class/drm/card0-HDMI-A-2/dpms:Off

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