linux-kernel - Re: KMS Framebuffer on Intel N2600 (GMA3600)

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Date:	Wed, 14 Nov 2012 17:17:55 +0000
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	Forconi <forconi@...ecomm.it>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: KMS Framebuffer on Intel N2600 (GMA3600)

> This backlight problem appears only when I run linux with KMS framebuffer,
> when I run linux without KMS framebuffer, the backlight is always on.
> 
> Yes, I have ACPI enabled and ACPI backlight enabled, but running:
> echo 100 > /sys/class/backlight/psb-bl/brightness

psb-bl/backlight willbe the backlight of the graphics not the ACPI
driver. You may need to enable that and also hack the acpi_video code to
add it anyway on that device.

> But, in the end, this means that the driver si correctly loaded and the 
> framebuffer is running but the panel backlight is off?
> In other words, I can't see anything only because the backlight is off?

I think so.

> I don't know which could be the maximum value, there are any standard values
> for backlight settings? I could try setting some values and see what happens...

Unfortunately not - and I have no idea what overdriving it would do to
the hardware.

Alan
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