drm/i915: Fix gen6 (SNB) missed BLT ring interrupts.
authorDaniel J Blueman <daniel.blueman@gmail.com>
Fri, 17 Jun 2011 18:32:19 +0000 (11:32 -0700)
committerDave Airlie <airlied@redhat.com>
Fri, 17 Jun 2011 22:25:16 +0000 (08:25 +1000)
commit498e720b96379d8ee9c294950a01534a73defcf3
tree85e1a5bf650087ea62d7f5c7fb56820f5a193790
parent95d17b7168eacf1f97f2d1d087ebe7a648c30051
drm/i915: Fix gen6 (SNB) missed BLT ring interrupts.

The failure appeared in dmesg as:

[drm:i915_hangcheck_ring_idle] *ERROR* Hangcheck timer elapsed... blt
ring idle [waiting on 35064155, at 35064155], missed IRQ?

This works around that problem on by making the blitter command
streamer write interrupt state to the Hardware Status Page when a
MI_USER_INTERRUPT command is decoded, which appears to force the seqno
out to memory before the interrupt happens.

v1->v2: Moved to prior interrupt handler installation and RMW flags as
per feedback.
v2->v3: Removed RMW of flags (by anholt)

Cc: stable@kernel.org
Signed-off-by: Daniel J Blueman <daniel.blueman@gmail.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Tested-by: Chris Wilson <chris@chris-wilson.co.uk> [v1]
Tested-by: Eric Anholt <eric@anholt.net> [v1,v3]
   (incidence of the bug with a testcase went from avg 2/1000 to
   0/12651 in the latest test run (plus more for v1))
Tested-by: Kenneth Graunke <kenneth@whitecape.org> [v1]
Tested-by: Robert Hooker <robert.hooker@canonical.com> [v1]
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=33394
Signed-off-by: Dave Airlie <airlied@redhat.com>
drivers/gpu/drm/i915/i915_irq.c