[Intel-gfx] Screen unusable for console until X starts (945GM)

[Daniel Vetter]

On Sat, Oct 20, 2012 at 2:14 PM, Rolf Eike Beer <eike-kernel at sf-tec.de> wrote:
> Am Samstag 20 Oktober 2012, 13:57:37 schrieb Daniel Vetter:
>> On Sat, Oct 20, 2012 at 8:30 AM, Rolf Eike Beer <eike-kernel at sf-tec.de>
> wrote:
>> > I have an older Laptop with this card in it:
>> >
>> > [    0.813208] agpgart-intel 0000:00:00.0: Intel 945GM Chipset
>> > [    0.813284] agpgart-intel 0000:00:00.0: detected gtt size: 262144K
>> > total, 262144K mappable
>> > [    0.814188] agpgart-intel 0000:00:00.0: detected 8192K stolen memory
>> > [    0.814377] agpgart-intel 0000:00:00.0: AGP aperture is 256M @
>> > 0xc0000000
>> >
>> > I observe the following strange behavior: if I start up the system (grub2,
>> > openSUSE 12.1) I see the splash screen appearing shortly. In most cases it
>> > will then disappear and the screen will become just black. This is not the
>> > delay "X is loading but has not put anything on the screen", but it is
>> > much
>> > earlier. I'm asked for a crypt password during bootup, which in most cases
>> > now happens totally in the dark, i.e. no console messages at all, no
>> > prompt. Booting just to runlevel 3 leaves me with a black screen but a
>> > functional system.
>> >
>> > The strange thing is: sometimes (like 10%) things are just working, i.e. I
>> > have console output. I've tested with 3.1.10 as well as 3.6.2 and both
>> > have
>> > the problem. I've run a number of 2.6 kernels before on this system, but I
>> > do not recall when the problem occured or which is one that definitely
>> > worked.
>> >
>> > Starting X will always get the screen back into working state, i.e. the
>> > system is normally usable after startup, but it is just annoying to see
>> > nothing during startup.
>> >
>> > Any hints, patches, whatever?
>>
>> Please attach drm.debug=0xe to your kernel cmdline, boot 3.6 and
>> attach complete dmesg (up to the point where X makes something appear
>> on the screen).
>
> Attached. Since I did not mention it earlier: from the moment on X is started
> consoles also work fine.

Another case where something sets the backlight brightness to zero
when we take over, and the X restores it to something sane again. If
the backlight keys on your machine work, you should be able to
brighten things up even before X starts.

Adding Jani since he's recently looked at an eerily similar bug.

Cheers, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch