[Intel-gfx] No boot console/Plane B assertion value on 945GM hardware

[Daniel Vetter]

On Mon, Jul 07, 2014 at 06:40:20PM +0200, Thomas Richter wrote:
> On 07.07.2014 17:04, Daniel Vetter wrote:
> >On Sat, Jun 21, 2014 at 01:57:32PM +0200, Thomas Richter wrote:
> >>Hi Daniel, dear intel experts,
> >>
> >>this a bug report for the intel i945GM integrated graphics chipset (*NOT*
> >>the 830GM this time). Since at least 3.12.0, but also with the latest
> >>intel-drm-nightly, I have no boot console on the 945GM chipset, the screen
> >>just remains blank. /var/log/messages  shows an assertion failure, see the
> >>attached kernel log for details, booted with drm.debug=0x0e.
> >>
> >>The problem appears if the kernel is booted with the vga=792 option  - note
> >>that the panel in this laptop is a 1024x768 and thus this is the native
> >>resolution. The problem does not appear with a text console.
> >>
> >>This sounds remarkably similar to the deadlock the 830GM had a while ago
> >>when booting with a graphical console, also with vga=792.
> >
> >Should be unrelated - more likely it's some fumble in the modeset
> >sequence, i945 is known to be picky in that area. Just to confirm: Latest
> >3.16-rc kernels are still broken?
> 
> At least 3.16-rc from one and a half week ago is affected, too. I'm
> currently not in reach of the machine - actually almost as far appart as
> possible.
> 
> >Can you please boot with drm.debug=0xe and grab a new dmesg with the
> >backtrace?
> 
> I'll try next week. What do you mean by "backtrace" apart from
> drm.debug=0x0e?

Just the entire dmesg up to the WARNING.

> >>As soon as X is initialized, graphics work again, I just don't have a boot
> >>console.
> >
> >So once X is running fbcon also works again, i.e. it's only the initial
> >boot console that's black?
> 
> Exactly. Once X is up, the console is fine again, too.
> 
> Greetings from Sapporo (<- which explains my unavailability),

Ok, enjoy your stay then ;-)
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch