DPMS broken on ThinkPad T43 since update for amd64 support

[Ian Smith]

On Thu, 18 Mar 2010, Kevin Oberman wrote:
 > Since the update of DPMS to support amd64 on March 2, it has broken
 > rather badly on my ThinkPad T43 laptop. The problem showed up on
 > 8-stable built on March 3 and is still present after an update to stable
 > of March 17.
 > 
 > When in vty text mode, after the idle normal delay, the display blanks,
 > but the backlight remains on, so the P in DPMS seems to be less than
 > effective. At that point, the non-graphics display is dead. It never
 > comes back when characters are entered. I can't get the display to come
 > back without a reboot.
 > 
 > I can, however, start X (and Gnome) and everything is fine. But
 > switching back to any vty results in a blank screen.
 > 
 > Any idea what happened and if there is a fix or workaround? Any data I
 > can collect?

Have you tried kldloading vesa?  Might be a workaround until you find a 
proper fix?  Had a similar issue with my T23 at one stage on 7.0, after 
a suspend/resume cycle, which hw.syscons.sc_no_suspend_vtswitch=1 also 
helped .. no idea how the T43 might respond to the latter.

FWIW, Ian