Bug#488277: xserver-xorg-video-radeon: No longer uses correct resolution when a second screen is connected

[Alex Deucher]

On Sat, Jun 28, 2008 at 11:07 AM, Torquil Macdonald Sørensen
<torquil at gmail.com> wrote:
> On Saturday 28 June 2008 01:11:51 Alex Deucher wrote:
>> On Fri, Jun 27, 2008 at 10:35 AM, Torquil Macdonald Sørensen
>>
>> <torquil at gmail.com> wrote:
>> > Package: xserver-xorg-video-radeon
>> > Version: 1:6.8.192-1
>> > Severity: normal
>> >
>> > Up until the last few days, when I started my laptop (1400x1050) with an
>> > external screen (LCD 1280x1024), X would automatically lower the
>> > resolution so that it was appropriate for the external screen, instead of
>> > the 1400x1050 it normally uses on my laptop (IBM T24 with ATI Radeon
>> > Mobility 9600). It doesn't do that any more.
>>
>> This is an xserver change.
>>
>> > Now I get a cropped 1400x1050 on the external LCD instead. E.g. I can
>> > only see the upper half of the KDE panel on the external screen. The
>> > lowest part of the desktop is not shown.
>>
>> The xserver mode default mode chooser has changed.  Nothing to do with
>> the driver.  removing the "Modes" line from your config may fix it:
>> Modes "1400x1050" "1280x1024" "1280x960" "1024x768" "800x600"
>> "700x525" "640x480"
>
> Removing the Modes line (in fact I removed DefaultDepth + Entire "Display"
> subsection from the Screen Section) had no effect on this.
>
>> > When I try to lower the resolution to 1280x1024 using kcontrol, the
>> > external screen becomes black and a 1280x1024 image is shown only on the
>> > laptop screen.
>>
>> kcrontrol is probably not xrandr 1.2 compliant and probably uses the
>> old xrandr 1.0 API which only affect one of the outputs and leads to
>> problems on multi-head systems.
>
> Ok, maybe kcontrol isn't up to the job, I have heard before that it does not
> support xrandr 1.2. I tried to use xrandr manually to change the desktop size
> using xrandr with --mode and --output options. I managed to get a 1280x1024
> resolution on the laptop screen after putting the "Modes" line back into
> xorg.conf (otherwise 1280x1024 was not listed as a mode for the LVDS). But
> the desktop image was cropped at the bottom on both screens. I did not manage
> to get a 1280x1024 "desktop geometry" to correspond to the 1280x1024 screen
> resolutions on the LVDS and external screen. But I will do some more
> investigating on how the xrandr command works, I guess there is some way to
> do it.

if you want both heads at 1280x1024, the following should do the trick:
xrandr --output LVDS --mode 1280x1024
xrandr --output VGA-0 --mode 1280x1024

It's up to kde to resize the various desktop elements when the modes change.

Alex