Re: Screen goes blank @30 seconds into boot

[Keith Packard <keithp@keithp.com>]

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On Thu, 26 Jan 2012 06:54:48 -0500, Joel Heaton <jheaton5@comcast.net> wrote:
> System: Dell Inspiron One
> Chipset: intel H61 Express
> CPU: Intel Pentium Dual Core Intel Core i3/i5i7 (this machine is
> probably an i3
> Video: Intel HD/HD 2000/HD 3000
> Max Resolution: 1920x1080
> OS-1 Windows 7 (shipped with this OS)
> OS-2 Debian Sid liquorix kernel 3.2
> 	DE: lxde no DM  I start x manually
> =========================================
> When booting the screen goes blank about 80% through the boot cycle.
> The system is still running, I can log in blind and execute reboot
> command.

Is the monitor backlight on or off? If off, can you try finding a bright
light and shining it on the monitor to see if the image is present, but
the backlight simply disabled?

> I ssh into the system from another computer.
> kern.log reports "Firmware Bug: ACPI: No _BQC method, cannot determine
> initial brightness"

The last bug we saw with this was a system that did leave the monitor
off. Here's a patch that fixed that machine:

Keith Packard <keithp@keithp.com> (December 31) (lkml me patch sent)
Subject: [PATCH] acpi/video: Don't restore backlight to 0 at boot time
To: linux-kernel@vger.kernel.org
Cc: Keith Packard <keithp@keithp.com>, Bdale Garbee <bdale@gag.com>, Matthew Garrett <mjg@redhat.com>
Date: Sat, 31 Dec 2011 00:52:27 -0800

If the initial ACPI reported backlight level is zero, or larger than
max_level, then ignore it and set the level back to the current level
instead. This avoids ending up with a black screen on an HP Pavilion
G series G4 notebook QE040UA#ABA.

Reported-by: Bdale Garbee <bdale@gag.com>
Cc: Bdale Garbee <bdale@gag.com>
Cc: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Keith Packard <keithp@keithp.com>
---
 drivers/acpi/video.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index 08a44b5..688f342 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -711,7 +711,7 @@ acpi_video_init_brightness(struct acpi_video_device *device)
		 * when invoked for the first time, i.e. level_old is invalid.
		 * set the backlight to max_level in this case
		 */
-		if (use_bios_initial_backlight) {
+		if (use_bios_initial_backlight && 0 < level_old && level_old <= max_level) {
			for (i = 2; i < br->count; i++)
				if (level_old == br->levels[i])
					level = level_old;
-- 
1.7.7.3

-- 
keith.packard@intel.com

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