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When my computer boots up, the LCD backlight is completely blank. I have to increase the brightness using the keys on my keyboard, and only then am I able to see the login screen.

I'm not sure how the 'fn' keys work on the HP Spectre XT Ultrabook, however, it seems to be enabled by default. That is, I don't have to hold down the 'fn' key when trying to decrease (f2) or increase (f3) the screen's brightness.

In an earlier issue with Ubuntu 12.10 on my machine, I needed to modify a line in my grub menu from:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX="acpi=off"

to,

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX=""

It's after making this change that the blank screen on booting up became an issue.

Further, I have read the following entry on the ubuntu wiki around the backlight and if I'm recognizing the problem as:

Hotkeys change the brightness, but no OSD feedback and the brightness applet does not work.

then, it says the following:

There is nothing that the kernel can do to resolve this situation. Since there is no vendor specific control mechanism and the generic ACPI interface is not defined (or not defined correctly), there is no way Linux can interact. In those cases the hotkeys are directly wired to the backlight control and no events are passed on to the OS.

What can I do, to not have to manually increase the brightness each time my computer boots up?

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marked as duplicate by Mitch, Eric Carvalho, green7, Luis Apr 19 '13 at 14:36

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

1 Answer 1

I needed to modify the GRUB once again.

I changed the entry from:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX=""

to:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"
GRUB_CMDLINE_LINUX=""

Now, when my computer boots up, the LCD backlight is at max brightness. I have to decrease the brightness manually, but I'm glad to be able to see the login screen.

(Apologies) my question seems to be a duplicate. Found the answer here.

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