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

[Jhih-Sin Chen]

On Wed, Jun 25, 2008 at 10:26 PM, Alex Deucher <alexdeucher at gmail.com> wrote:
> 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
>

Hi,

But I can't use xrandr to swtich display device to HDMI. Is it a
limitation of xrandr or anything wrong?

So I wanna use VBIOS to switch display device. Could you kindly tell
me how to enabled VBIOS switch function on xf86-video-ati or give a
start point for me to study? Thanks.