Bug#662348: i915: please save more useful debugging info when GPU locks up

[Jonathan Nieder <jrnieder@gmail.com>]

Source: linux-2.6
Version: 2.6.32-41
Severity: wishlist
Tags: upstream patch

After an i915 GPU hang, apparently[*] the most convenient and useful
information a person can provide is the last batch buffer.  A patch
applied in the 2.6.34 merge window taught the driver to save this
information on error:

  9df30794f609 "drm/i915: Record batch buffer following GPU error" 2010-02-18

Ben, would the attached patches make sense for squeeze?  (Warning:
untested.  I don't have a machine using Intel graphics.)

With the first applied, one can do the following after a GPU hang.

	mount -t debugfs debugfs /sys/kernel/debug
	cat /sys/kernel/debug/dri/0/i915_error_state >i915_error_state

A later patch adds a notice inviting the user to do that to the kernel
log.

The patches do not seem very risky (the first one adds the error state
collection feature and the ones afterwards are minor tweaks I noticed
while hunting for potential bugfixes relating to that), but this is
more complication than stable_kernel_rules.txt encourages.  So these
are not meant as candidates for inclusion in 2.6.32.y+drm33.z.

[*] judging from <http://intellinuxgraphics.org/how_to_report_bug.html>:
"for GPU hang, get the last batch buffer (see the guide)".

Chris Wilson (4):
  drm/i915: Record batch buffer following GPU error
  drm/i915: Only print an message if there was an error
  drm/i915: Only print 'generating error event' if we actually are
  drm/i915: Include 'i915_error_state' hint for when the GPU catches
    fire

Daniel Vetter (2):
  drm/i915: unload: fix error_work races
  drm/i915: unload: don't leak error state

 drivers/gpu/drm/i915/i915_debugfs.c |   85 +++++++++++
 drivers/gpu/drm/i915/i915_dma.c     |   10 +-
 drivers/gpu/drm/i915/i915_drv.h     |   21 +++
 drivers/gpu/drm/i915/i915_gem.c     |    2 +-
 drivers/gpu/drm/i915/i915_irq.c     |  266 ++++++++++++++++++++++++++++++++---
 drivers/gpu/drm/i915/i915_reg.h     |    1 +
 6 files changed, 359 insertions(+), 26 deletions(-)