VBIOS can't switch to external device when I use xf86-video-ati driver

[Alex Deucher]

On Wed, Jun 25, 2008 at 9:56 AM, Jhih-Sin Chen <jschen.cse at gmail.com> wrote:
> Hi,
>
> I am using Radeon HD 3470 card with xf86-video-ati 6.8.192 on my laptop.
> I try to implement hotkey function to switch display device.
> I have set _DOS parameter in ACPI and ask VBIOS to switch display
> device but it fails.
>
> However, the hotkey function can switch display device successfully
> when I use "vesa" driver.
> Do you have any suggetion on this issue? Thanks.

It's disabled on purpose.  The bios goes behind the driver's back and
messes with the hardware which can lead to bad state or possibly hw
locks.  You can control the outputs with xrandr so please use that.
On most laptops you can even change the video hotkey to produce acpi
events rather than banging the hw directly and then you tie that event
to a script that runs xrandr commands.

Alex