drm/i915: Replace vblank PM QoS with "Interrupt-Based AGPBUSY#"
authorChris Wilson <chris@chris-wilson.co.uk>
Sat, 5 Feb 2011 10:08:21 +0000 (10:08 +0000)
committerChris Wilson <chris@chris-wilson.co.uk>
Tue, 1 Mar 2011 17:33:38 +0000 (17:33 +0000)
commit8692d00e996ed2a6560702623e5cb646da0f9767
tree43d541c3ec2c06473c7c607965d256251b349513
parent60c8bdf64a80ebb0132172ea97bd54d7c7d36611
drm/i915: Replace vblank PM QoS with "Interrupt-Based AGPBUSY#"

I stumbled over this magic bit in the gen3 INSTPM:

Bit11 Interrupt-Based AGPBUSY# Enable:

‘0’ = Pending GMCH interrupts will not cause AGPBUSY# assertion.
‘1’ = Pending GMCH interrupts will cause AGPBUSY# assertion and hence
      can cause the CPU to exit C3.  There is no suppression of cacheable
      writes.

Note that in either case in C3 the interrupts are not lost. They will be
forwarded to the ICH when the GMCH is out of C3.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Tested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@kernel.org
drivers/gpu/drm/i915/i915_irq.c
drivers/gpu/drm/i915/i915_reg.h