drm/i915/gen4: Fix interrupt setup ordering
authorAdam Jackson <ajax@redhat.com>
Thu, 27 May 2010 21:26:45 +0000 (17:26 -0400)
committerEric Anholt <eric@anholt.net>
Sat, 5 Jun 2010 00:21:41 +0000 (17:21 -0700)
commitc496fa1fff0248ef8cd637efb52b70dea7afaa9d
treebbdc1b56f61f12d68509a2f927a9c777dc35eee7
parentf458823b864c6def488f951a79986fa205aba4f1
drm/i915/gen4: Fix interrupt setup ordering

Unmask, then enable interrupts, then enable interrupt sources; matches
PCH ordering.  The old way (sources, enable, unmask) gives a window
during which interrupt conditions would appear in ISR but would never
reach IIR and thus never raise an IRQ.  Since interrupts only trigger
on rising edges in ISR, this would lead to conditions where (for
example) output hotplugging would never fire an interrupt because it
was already stuck on in ISR.

Also, since we know IIR and PIPExSTAT have been cleared during
irq_preinstall, don't clear them again during irq_postinstall, nothing
good can come of that.

Signed-off-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
drivers/gpu/drm/i915/i915_irq.c