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Date: Fri, 15 Mar 2013 02:33:11 -0700
Message-ID: <CANeU7Q=J8C1Gdd7kNbwQXD+5oka4XEmEo=bmKHbDU3UVcxtEHA@mail.gmail.com>
Subject: Re: [Intel-gfx] i915 black screen introduced by ACPI changes
From: Chris Li <lkml@chrisli.org>
To: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>, len.brown@intel.com,
        feng.tang@intel.com, intel-gfx <intel-gfx@lists.freedesktop.org>,
        linux-kernel@vger.kernel.org, robert.moore@intel.com,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Zhang Rui <rui.zhang@intel.com>
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On Fri, Mar 15, 2013 at 12:29 AM, Jani Nikula
<jani.nikula@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
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