[Bug 172421] radeon: allow to set the TMDS frequency by a special kernel parameter

https://bugzilla.kernel.org/show_bug.cgi?id=172421

--- Comment #16 from Christian König deathsimple@vodafone.de --- (In reply to Roland Scheidegger from comment #15)

Oh interesting - didn't know voltage was directly tied to clock frequency here. Makes sense then to not allow it (at least if that circuitry isn't shared with DP, as the DP link runs at much higher clock (540Mhz actually), but I suppose it's really different there).

The voltage is only indirectly related, but yes over clocking such parts is a rather bad idea in the long term.

DP uses a fixed frequency which is way easier to generate than the variable HDMI/DVI/VGA clock.