There are two separate issues here :
1. The X server is not reporting a mode which you feel your TV can support
2. When you try to switch modes to 1920x540 via KDE something goes wrong and there's no record in the log
Using xrandr will immediately help with #2. You can also use xrandr to add a mode but you'll need the same timing info as if you were adding a modeline in xorg.conf.
xrandr shows the following.
Screen 0: minimum 320 x 200, current 1280 x 720, maximum 1920 x 1920
VGA-0 disconnected (normal left inverted right x axis y axis)
HDMI-0 connected 1280x720+0+0 (normal left inverted right x axis y axis) 920mm x 518mm
I'm fine with running the machine at 720p if it's a choice between that and 1080i. My tv's native resolution is 1366x768 so there's not much loss here. 1080p probably would have only been slightly better.
Yeah, if your screen resolution is 1366x768 then the main reason for a 1080 input is to support players or tuners which can't upscale or downscale. That also explains why 720p is the preferred resolution rather than 1080i.
OK, wait a second....
Originally Posted by ben0
The Television in question, which you have reported working at 1080p in the past has a native resolution on 1366x768..... I think you must have had some kind of downscaling option set in fglrx somewhere that allowed the driver to switch to 1080p resolution, but which was downscaled to 720p before it was output to the television.
I've never used fglrx before though, so you'll just have to look through it's configuration and find the options for upscaling and downscaling