On Sat, Feb 09, 2013 at 09:03:42PM +0100, Daniel Vetter wrote: > Some early bios versions seem to ship with the wrong tuning values for > the MCH, possible resulting in pipe underruns under load. Especially > on DP outputs this can lead to black screen, since DP really doesn't > like an occasional whack from an underrun. > > Unfortunately the registers seem to be locked after boot, so the only > thing we can do is politely point out issues and suggest a BIOS > upgrade. > > Arthur Runyan pointed us at this issue while discussion DP bugs - thus > far no confirmation from a bug report yet that it helps. But at least > some of my machines here have wrong values, so this might be useful in > understanding bug reports. > > v2: After a bit more discussion with Art and Ben we've decided to only > the check the watermark values, since the OREF ones could be be a > notch more aggressive on certain machines. > > Cc: Ben Widawsky <ben at bwidawsk.net> > Cc: Runyan, Arthur J <arthur.j.runyan at intel.com> > Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch> I wouldn't mind if you printed the OREF values, even if you didn't use them to detect. But, Reviewed-by: Ben Widawsky <ben at bwidawsk.net> [snip] -- Ben Widawsky, Intel Open Source Technology Center
