Re: post-rc4 regression (bisected): blank screen on ASUS P5KPL-AM

[Maciej Rutecki <maciej.rutecki@gmail.com>]

Similar (or the same):
https://bugzilla.kernel.org/show_bug.cgi?id=25242

On poniedziałek, 20 grudnia 2010 o 15:06:16 Jochen Voss wrote:
> Hello,
> 
> My system, when booted with recent kernels, fails to show any output
> on the monitor.  The problem occurs very early during bootup (I never
> see anything after the messages from grub), the monitor indicates that
> there is no video signal at all and dmesg shows the following lines:
> 
> [    1.540465] usbhid: USB HID core driver
> [    2.490014] No connectors reported connected with modes
> [    2.490019] [drm] Cannot find any crtc or sizes - going 1024x768
> [    2.496064] Console: switching to colour frame buffer device 128x48
> [    2.497729] fb0: inteldrmfb frame buffer device
> 
> The machine seems fine otherwise: I can log in remotely and logging in
> from the console (by typing blindly without visual feedback) also
> works.
> 
> The problem is present in the current kernel as of this morning (I see
> it with commit 55ec86f848a5f872fd43f5d7206464a0af419110).  Bisection
> indicates that it is caused by the following commit.
> 
>     commit 541cc966915b6756e54c20eebe60ae957afdb537
>     Author: Chris Wilson <chris@chris-wilson.co.uk>
>     Date:   Mon Dec 6 11:24:07 2010 +0000
> 
> 	drm: Don't try and disable an encoder that was never enabled
> 
> 	Prevents code that assumes that the encoder is active when
> 	asked to be disabled from dying a horrible death.
> 
> 	Reported-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> 	Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> 	Signed-off-by: Dave Airlie <airlied@redhat.com>
> 
> I verfied that the problem disappears when booting recent kernels
> (i.e. 55ec86f848a5f872fd43f5d7206464a0af419110) with the offending
> commit reverted.  The screen works again and the dmesg output now
> changes to
> 
> [    1.542515] usbhid: USB HID core driver
> [    1.547569] Console: switching to colour frame buffer device 210x65
> [    1.551558] fb0: inteldrmfb frame buffer device
> 
> Note that the one second wait which was present in the bad dmesg
> has now disappeared.
> 
> System information:
> 
>     ASUS P5KPL-AM mainboard (Intel G31 chipset)
>     Intel Core2 quad core CPU
>     Ubuntu 10.10
> 
> Appended files:
> 
>     dmesg.bad: dmesg for 55ec86f848a5f872fd43f5d7206464a0af419110
>     dmesg.good: dmesg for 55ec86... with
>         541cc966915b6756e54c20eebe60ae957afdb537 reverted
>     lspci: "lspci -v" output (on a good kernel)
> 
> I'd be happy to send further information or to try patches etc.
> 
> I hope this helps,
> Jochen

-- 
Maciej Rutecki
http://www.maciek.unixy.pl