[Intel-gfx] i915 black screen introduced by ACPI changes

[Chris Li]

On Mon, Mar 11, 2013 at 6:16 AM, Jani Nikula
<jani.nikula at linux.intel.com> wrote:
> Interesting snippets from your dmesgs:
>
> 1) good
>
> [    0.000000] Linux version 3.6.0-rc6+ (chrisl at ideapad.lan) (gcc version 4.7.2 20121109 (Red Hat 4.7.2-8) (GCC) ) #25 SMP Wed Feb 20 12:55:06 PST 2013
> ...
> [    5.341431] [drm:intel_panel_get_max_backlight], max backlight PWM = 4648
> [    5.341442] [drm:intel_panel_actually_set_backlight], set backlight PWM = 4648
> [    5.342572] [drm:intel_panel_get_max_backlight], max backlight PWM = 4648
> [    5.342578] [drm:intel_panel_actually_set_backlight], set backlight PWM = 4648
>
> 2) bad
>
> [    0.000000] Linux version 3.8.0-rc7+ (chrisl at ideapad.lan) (gcc version 4.7.2 20121109 (Red Hat 4.7.2-8) (GCC) ) #23 SMP Tue Feb 19 19:24:57 PST 2013
> ...
> [    5.692853] [drm:asle_set_backlight], bclp = 0x800000ff
> [    5.692865] [drm:intel_panel_get_max_backlight], max backlight PWM = 4648
> [    5.692870] [drm:intel_panel_actually_set_backlight], set backlight PWM = 4648
> [    5.693401] [drm:asle_set_backlight], bclp = 0x80000000
> [    5.693408] [drm:intel_panel_get_max_backlight], max backlight PWM = 4648
> [    5.693413] [drm:intel_panel_actually_set_backlight], set backlight PWM = 0
>
> (We've added another debug print to asle_set_backlight.)
>
> For some reason we get two asle requests in a row. In the good kernel
> it's the same request twice, in the bad kernel the second requests is
> for 0 backlight. The register dumps seem to confirm this.
>
> Please try a recent kernel, with and without the the bisected bad commit

Hi, I did try the tip of Linus git tree. However I can't make the kernel
boot regardless bad commit or not. The kernel just hang there after grub2
load the kernel and initram image. It looks like a different problem than the
intel black screen because it don't even get to the point show any console
print out.

I will try the intel branch instead.

Chris