[Intel-gfx] Pipe CRCs v1

[Damien Lespiau]

This series exposes the pipe CRCs on ivybridge through debugfs. It's based on
the initial work from Shuang He, with some improvements to have a nice user
space API.

There are several points in the display pipeline where CRCs can be computed
on the bits flowing there. For instance, it's usually possible to compute
the CRCs of the primary plane, the sprite plane or the CRCs of the bits
after the panel fitter (collectively called pipe CRCs).

An intel-gpu-tools series will follow with helpers to use the feature from
tests and basic testing.

Further work items:
  * make it work on other platforms
  * expose other CRCs than just the pipe CRCs (transcoders, ddi, ...)
  * implement poll() for the result files

-- 
Damien

 drivers/gpu/drm/i915/i915_debugfs.c | 503 ++++++++++++++++++++++++++--
 drivers/gpu/drm/i915/i915_dma.c     |   2 +
 drivers/gpu/drm/i915/i915_drv.h     |  31 ++
 drivers/gpu/drm/i915/i915_irq.c     |  49 +++
 drivers/gpu/drm/i915/i915_reg.h     |  36 +-
 5 files changed, 594 insertions(+), 27 deletions(-)