drm/radeon/kms/r6xx+: use new style fencing (v3)

On r6xx+ a newer fence mechanism was implemented to replace
the old wait_until plus scratch regs setup.  A single EOP event
will flush the destination caches, write a fence value, and generate
an interrupt.  This is the recommended fence mechanism on r6xx+ asics.

This requires my previous writeback patch.

v2: fix typo that enabled event fence checking on all asics
rather than just r6xx+.

v3: properly enable EOP interrupts
Should fix:
https://bugs.freedesktop.org/show_bug.cgi?id=29972

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/evergreen.c b/drivers/gpu/drm/radeon/evergreen.c
index e47d221..4c82cc8 100644
--- a/drivers/gpu/drm/radeon/evergreen.c
+++ b/drivers/gpu/drm/radeon/evergreen.c
@@ -1594,6 +1594,7 @@
 	if (rdev->irq.sw_int) {
 		DRM_DEBUG("evergreen_irq_set: sw int\n");
 		cp_int_cntl |= RB_INT_ENABLE;
+		cp_int_cntl |= TIME_STAMP_INT_ENABLE;
 	}
 	if (rdev->irq.crtc_vblank_int[0]) {
 		DRM_DEBUG("evergreen_irq_set: vblank 0\n");
@@ -2012,6 +2013,7 @@
 			break;
 		case 181: /* CP EOP event */
 			DRM_DEBUG("IH: CP EOP\n");
+			radeon_fence_process(rdev);
 			break;
 		case 233: /* GUI IDLE */
 			DRM_DEBUG("IH: CP EOP\n");