Messages in this thread | | | Date | Wed, 14 Oct 2009 22:26:45 -0400 | From | Theodore Tso <> | Subject | Re: 2.6.32 regression (bisected): Video tearing/glitching with T400 laptops |
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On Wed, Oct 14, 2009 at 02:22:52PM -0700, Jesse Barnes wrote: > On Tue, 13 Oct 2009 12:14:26 -0700 > Jesse Barnes <jbarnes@virtuousgeek.org> wrote: > > According to the chipset team that form of display corruption is > > likely related to RAM self-refresh... Sounds like the display plane > > isn't getting its memory requests serviced fast enough when in > > self-refresh mode, which might mean we have to program the > > self-refresh watermarks more aggressively on GM45. > > Ok, like any good bug there was more than one thing wrong: > - we weren't setting up a fence for the object before enabling FBC. > Chris caught this and posted a patch to > intel-gfx@lists.freedesktop.org titled "drm/i915: Install a fence > register for fbc on g4x" (attached for convenience) > - turns out we *do* need to set watermarks on G4x, despite some hw > documentation indicating otherwise, patch for that attached > > Hopefully with these two you'll have a solid display and some power > saving!
With these two patches (and none of your prior ones) applied to 2.6.32-rc3, things are definitely better. I'm still seeing a few glitches (one as mutt was loading my Maildir inbox) and one as I was typing this message in emacs, but it's at best one minor every 5-10 minutes. It's rare enough to be at most a wee bit distracting (*lots* better than before), and I can see the power savings.
If I need to live with a display glitch every 5-10 minutes or so to get better power savings, I'll take it....
- Ted
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