[Intel-gfx] [PATCH 0/4] gtt cache coherency checker for i830 class hw

[Daniel Vetter]

Hi all,

This is part of my try-to-fix-i855-cache-coherency patch. It's essentially
everything save the actual hacks to fix the gtt chipset flush (that simply not
yet ready). The most important part is the cache coherency checker. I think
merging this without any other fixes is worth it for a few reasons:

- easier i8xx bug triaging: "random" crashes without any other applicable
  known issues but with some WARN_ONs due to failed chipset flushes
  suddenly get a decent explanation.
- better assessment of how widespread this problem is: Given that my
  Thinkpad X40 happily spits out these traces when under use but is
  otherwise rather stable, we'll likely see a surge of bug reports. Perhaps
  even a top-ten spot on kerneloops.org :( ...
- and one purely selfish reason: The patch I'm carrying around gets smaller
  ;)

I've thought about whether to include a bz link in the dmesg output, but
couldn't really decide one way or another. I fear that bz entry will get
swamped under by totally useless me-too-and-all-intel-devs-suck reports.
But on the other hand it's not really nice to waste testers time (creating
nice bug reports) by not telling them that this is a know issue and where
progress is tracked.

Comments highly welcome. And when testing, don't get scared - at least on
i855 getting the first failed flush before gdm finished drawing the login
screen is kinda expected ;)

Patches rebased against my two outstanding agp/gtt split-up patches, but should
work on top of latest drm-intel-next, too.

Yours, Daniel

Daniel Vetter (4):
  agp/intel-gtt: steal the last gtt page
  drm/i915: add locking around chipset flush
  agp/intel-gtt: check cache-coherency on i830 class chipsets
  agp/intel-gtt: extract mch buffer flush in i830 chipset flush

 drivers/char/agp/intel-gtt.c    |  163 +++++++++++++++++++++++++++++++--------
 drivers/gpu/drm/i915/i915_dma.c |    4 +-
 drivers/gpu/drm/i915/i915_gem.c |    3 +
 include/drm/intel-gtt.h         |    8 ++
 4 files changed, 146 insertions(+), 32 deletions(-)
 create mode 100644 include/drm/intel-gtt.h