Display on HDMI-connected TV to large

[Alex Deucher]

On Fri, Feb 19, 2010 at 6:23 PM, Sebastian Beßler
<sebastian at darkmetatron.de> wrote:
>> On Fri, Feb 19, 2010 at 5:01 PM, Sebastian Beßler
>> <sebastian at darkmetatron.de> wrote:
>>>> On Fri, Feb 19, 2010 at 2:37 PM, Sebastian Beßler
>>>> Some TV's enable overscan by default.  Turn off overscan on your tv.
>>>> The
>>> option might be called "fit" or "exact" or something like that. The
>>> other alternative is to underscan the modeline sent to your
>>>> monitor.  Google for "underscan modeline"
>>>
>>> I can't disable overscan in my TV.
>>> I can switch a few modes but non of them help because the modes which
>>> change something only steal more but no mode gives.
>>>
>>> Underscan doesn't seem to help too. I tried down to 1064x504 in steps of
>>> 8
>>> (from 1280x720) and my TV always seems to compensate.
>>>
>>> What I don't understand is, that all just worked with fglrx drivers and
>>> zaphod mode. No overscan at all. That looks like a driver issue to me.
>>
>> fglrx adjusts the modeline for underscan the same way.
>
> Then maybe I am just too stupid to get something right that fglrx had
> magically done without any configuration from my side.
>
> Sorry, it is late here and I run out off ideas and endurance for today.

You need to adjust the display area of the mode relative to the total.
 For example:
Modeline "1280x720"                   74.50  1280 1344 1472 1664  720
723 728 748 -hsync +vsync
Modeline "1280x720underscan"  74.50  1170 1344 1472 1664  660 723 728
748 -hsync +vsync

Note that the total values are constant: 1650 -> 1650, 748 -> 748,
while the display values have been reduced: 1280 -> 1170, 720 -> 660.

Try one of those modes, or adjust your own based on the 1280x720
timing from your tv.  xrandr --verbose will print the full modeline.

here are some others I found on the web:
ModeLine "1176x664a" 74.250 1176 1390 1430 1650 664 725 730 750 +hsync +vsync
ModeLine "1176x664b" 74.250 1176 1338 1378 1650 664 697 702 750 +hsync +vsync
ModeLine "1200x670" 74.250 1200 1208 1248 1980 670 700 705 750 +hsync +vsync

Alex