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

[Chris Li]

On Fri, Mar 15, 2013 at 12:29 AM, Jani Nikula
<jani.nikula at linux.intel.com> wrote:

> Fun. The BIOS seems to ask for zero backlight. Maybe it means something
> else for Windows 8. White is the new black or something.

I did some experiment, I go to intel_backlight directory.
It show brightness is 4648, but actual_brightness is 0.
Then I do "echo 4648 > brightness", the screen actually
come back to light. X window function properly.

However, if I go to suspend and resume. It is black screen
again.

If I use the Fn+Brightness to adjust the brightness. It seems
the ACPI brightness is set to lowest. One press of "Fn+Brightness up"
will give me about 10% of the brightness. It does not feel like
white is the new black.

Chris