My HDTV (Toshiba 32RV530U) allows 1:1 pixel mapping, yet my video card (a Radeon 4850) insists on underscanning by default.

In windows this is pretty annoying, as it needs to be corrected for every resolution I use. But the drivers have a slider so it can at least be fixed fairly quickly. I've yet to run into a refresh rate / resolution combo that I haven't been able to correct.

Since the Linux drivers don't yet have this slider I've had to use instructions found here to disable the underscan ("aticonfig --initial" and "aticonfig --set-pcs-val=MCIL,DigitalHDTVDefaultUnderscan,0"). That works most of the time.

Is there a way to make this setting permanent? Can I send a command to the card and say 'please stop doing this, now and for the rest of your lifespan?'

Also, out of curiosity: what was the reason behind making them underscan by default, instead of just having the option there for TVs that required it? Do other cards in the 4000 series do this?