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

[Alex Deucher]

On Wed, Jun 25, 2008 at 10:50 AM, Jhih-Sin Chen <jschen.cse at gmail.com> wrote:
> 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?
>

what sort of problem are you having?
xrandr --output HDMI-0 --auto
should do the trick.

What does the output of xrandr look like?

> 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.
>

The driver doesn't use it.  It just disables the use of it.

Alex