[RS690] Display scaling for HDMI

[Hadmut Danisch]

Binary package hint: xserver-xorg-video-ati

Hi,

I have a small Acer desktop PC (actually built mostly from notebook technology), a
01:05.0 VGA compatible controller: ATI Technologies Inc RS690 [Radeon X1200 Series]
onboard graphics adapter and DVI and HDMI output.

The computer had a running hardy (8.04) installation and worked well with a regular DVI computer screen.
I recently removed that computer from the desktop and the DVI screen and put it to my video equipment,
connected to a (cheap) 1280x720 pixel LCD flatscreen TV with HDMI input. With hardy, it immediately
detected the screen resolution and displayed a screen that perfectly met the screen resolution.

Now I've upgraded to intrepid beta. Now I have the problem that the computer still recognizes the screen resolution 1280x720, but now displays an image larger than the actual screen resolution, i.e. the outer parts of the image are missing (about 70% of the top and bottem gnome bar) and the visible part of the image occurs as unsharp due to scaling effects.

I was not even aware that the computer could overscale the screen with a digital interface like with analog displays.

[Bryce Harrington (bryce)]

Please also attach the following information:
* xrandr --verbose
* /etc/X11/xorg.conf
* lspci -vvnn

[Hadmut Danisch (hadmut)]

BTW: The LCD TV claims (on the card package) to have a 1440x900 display.

[Hadmut Danisch (hadmut)]

Well, I guess I found the main problem:

The LCD TV seems to not be prepared to work as a computer monitor, but to display only Video signals, even on HDMI, so it does not tell the "HDMI sender", what resolutions it has, it tells what resolutions it will accept. The TV keeps scaling the video signal anyway to remove the common black bars, so one problem was that the TV is rescaling the image even when on HDMI.

To get the X11 screen displayed properly it takes two steps:

- force the resolution with xrandr -s 1440x900
- set the TV to 16:9 mode

So there should be a way to enforce a given resolution under Ubuntu.

regards

[Hadmut Danisch (hadmut)]

There's btw., another problem:

Video players like xine and mplayer cause extreme flickering. There's obviously anything wrong with the synchronization.

regards

[Bryce Harrington (bryce)]

"""
To get the X11 screen displayed properly it takes two steps:

- force the resolution with xrandr -s 1440x900
- set the TV to 16:9 mode

So there should be a way to enforce a given resolution under Ubuntu.
"""

Can you not do this with the Screen Resolution capplet? If not, maybe this should be filed as a wishlist bug against those config tools?

As to the flickering, please file a separate bug on that issue.

[Bryce Harrington (bryce)]

We're closing this bug since it is has been some time with no response from the original reporter. However, if the issue still exists please feel free to reopen with the requested information. Also, if you could, please test against the latest development version of Ubuntu, since this confirms the bug is one we may be able to pass upstream for help.