Petter Reinholdtsen

Fixing the Linux black screen of death on machines with Intel HD video
11th June 2013

When installing RedHat, Fedora, Debian and Ubuntu on some machines, the screen just turn black when Linux boot, either during installation or on first boot from the hard disk. I've seen it once in a while the last few years, but only recently understood the cause. I've seen it on HP laptops, and on my latest acquaintance the Packard Bell laptop. The reason seem to be in the wiring of some laptops. The system to control the screen background light is inverted, so when Linux try to turn the brightness fully on, it end up turning it off instead. I do not know which Linux drivers are affected, but this post is about the i915 driver used by the Packard Bell EasyNote LV, Thinkpad X40 and many other laptops.

The problem can be worked around two ways. Either by adding i915.invert_brightness=1 as a kernel option, or by adding a file in /etc/modprobe.d/ to tell modprobe to add the invert_brightness=1 option when it load the i915 kernel module. On Debian and Ubuntu, it can be done by running these commands as root:

echo options i915 invert_brightness=1 | tee /etc/modprobe.d/i915.conf
update-initramfs -u -k all

Since March 2012 there is a mechanism in the Linux kernel to tell the i915 driver which hardware have this problem, and get the driver to invert the brightness setting automatically. To use it, one need to add a row in the intel_quirks array in the driver source drivers/gpu/drm/i915/intel_display.c (look for "static struct intel_quirk intel_quirks"), specifying the PCI device number (vendor number 8086 is assumed) and subdevice vendor and device number.

My Packard Bell EasyNote LV got this output from lspci -vvnn for the video card in question:

00:02.0 VGA compatible controller [0300]: Intel Corporation \
    3rd Gen Core processor Graphics Controller [8086:0156] \
    (rev 09) (prog-if 00 [VGA controller])
 Subsystem: Acer Incorporated [ALI] Device [1025:0688]
 Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- \
    ParErr- Stepping- SE RR- FastB2B- DisINTx+
 Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- \
    SERR-  [disabled]
 Kernel driver in use: i915

The resulting intel_quirks entry would then look like this:

struct intel_quirk intel_quirks[] = {
        /* Packard Bell EasyNote LV11HC needs invert brightness quirk */
	{ 0x0156, 0x1025, 0x0688, quirk_invert_brightness },

According to the kernel module instructions (as seen using modinfo i915), information about hardware needing the invert_brightness flag should be sent to the dri-devel (at) mailing list to reach the kernel developers. But my email about the laptop sent 2013-06-03 have not yet shown up in the web archive for the mailing list, so I suspect they do not accept emails from non-subscribers. Because of this, I sent my patch also to the Debian bug tracking system instead as BTS report #710938, to make sure the patch is not lost.

Unfortunately, it is not enough to fix the kernel to get Laptops with this problem working properly with Linux. If you use Gnome, your worries should be over at this point. But if you use KDE, there is something in KDE ignoring the invert_brightness setting and turning on the screen during login. I've reported it to Debian as BTS report #711237, and have no idea yet how to figure out exactly what subsystem is doing this. Perhaps you can help? Perhaps you know what the Gnome developers did to handle this, and this can give a clue to the KDE developers? Or you know where in KDE the screen brightness is changed during login? If so, please update the BTS report (or get in touch if you do not know how to update BTS).

Update 2013-07-19: The correct fix for this machine seem to be acpi_backlight=vendor, to disable ACPI backlight support completely, as the ACPI information on the machine is trash and it is better to leave it to the intel video driver to control the screen backlight.

Tags: debian, english.

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