[RFC 44/44] drm/i915: Fake batch support for page flips

[John.C.Harrison@Intel.com]

From: John Harrison <John.C.Harrison@Intel.com>

Any commands written to the ring without the scheduler's knowledge can get lost
during a pre-emption event. This checkin updates the page flip code to send the
ring commands via the scheduler's 'fake batch' interface. Thus the page flip is
kept safe from being clobbered.
---
 drivers/gpu/drm/i915/intel_display.c |   84 ++++++++++++++++------------------
 1 file changed, 40 insertions(+), 44 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index fa1ffbb..8bbc5d3 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -9099,8 +9099,8 @@ static int intel_gen7_queue_flip(struct drm_device *dev,
 				 uint32_t flags)
 {
 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
-	uint32_t plane_bit = 0;
-	int len, ret;
+	uint32_t plane_bit = 0, sched_flags;
+	int ret;
 
 	switch (intel_crtc->plane) {
 	case PLANE_A:
@@ -9117,18 +9117,6 @@ static int intel_gen7_queue_flip(struct drm_device *dev,
 		return -ENODEV;
 	}
 
-	len = 4;
-	if (ring->id == RCS) {
-		len += 6;
-		/*
-		 * On Gen 8, SRM is now taking an extra dword to accommodate
-		 * 48bits addresses, and we need a NOOP for the batch size to
-		 * stay even.
-		 */
-		if (IS_GEN8(dev))
-			len += 2;
-	}
-
 	/*
 	 * BSpec MI_DISPLAY_FLIP for IVB:
 	 * "The full packet must be contained within the same cache line."
@@ -9139,13 +9127,7 @@ static int intel_gen7_queue_flip(struct drm_device *dev,
 	 * then do the cacheline alignment, and finally emit the
 	 * MI_DISPLAY_FLIP.
 	 */
-	ret = intel_ring_cacheline_align(ring);
-	if (ret)
-		return ret;
-
-	ret = intel_ring_begin(ring, len);
-	if (ret)
-		return ret;
+	sched_flags = i915_ebp_sf_cacheline_align;
 
 	/* Unmask the flip-done completion message. Note that the bspec says that
 	 * we should do this for both the BCS and RCS, and that we must not unmask
@@ -9157,32 +9139,46 @@ static int intel_gen7_queue_flip(struct drm_device *dev,
 	 * to zero does lead to lockups within MI_DISPLAY_FLIP.
 	 */
 	if (ring->id == RCS) {
-		intel_ring_emit(ring, MI_LOAD_REGISTER_IMM(1));
-		intel_ring_emit(ring, DERRMR);
-		intel_ring_emit(ring, ~(DERRMR_PIPEA_PRI_FLIP_DONE |
-					DERRMR_PIPEB_PRI_FLIP_DONE |
-					DERRMR_PIPEC_PRI_FLIP_DONE));
-		if (IS_GEN8(dev))
-			intel_ring_emit(ring, MI_STORE_REGISTER_MEM_GEN8(1) |
-					      MI_SRM_LRM_GLOBAL_GTT);
-		else
-			intel_ring_emit(ring, MI_STORE_REGISTER_MEM(1) |
-					      MI_SRM_LRM_GLOBAL_GTT);
-		intel_ring_emit(ring, DERRMR);
-		intel_ring_emit(ring, ring->scratch.gtt_offset + 256);
-		if (IS_GEN8(dev)) {
-			intel_ring_emit(ring, 0);
-			intel_ring_emit(ring, MI_NOOP);
-		}
-	}
+		uint32_t cmds[] = {
+			MI_LOAD_REGISTER_IMM(1),
+			DERRMR,
+			~(DERRMR_PIPEA_PRI_FLIP_DONE |
+				DERRMR_PIPEB_PRI_FLIP_DONE |
+				DERRMR_PIPEC_PRI_FLIP_DONE),
+			IS_GEN8(dev) ? (MI_STORE_REGISTER_MEM_GEN8(1) |
+					MI_SRM_LRM_GLOBAL_GTT) :
+				       (MI_STORE_REGISTER_MEM(1) |
+					MI_SRM_LRM_GLOBAL_GTT),
+			DERRMR,
+			ring->scratch.gtt_offset + 256,
+//		if (IS_GEN8(dev)) {
+			0,
+			MI_NOOP,
+//		}
+			MI_DISPLAY_FLIP_I915 | plane_bit,
+			fb->pitches[0] | obj->tiling_mode,
+			intel_crtc->unpin_work->gtt_offset,
+			MI_NOOP
+		};
+		uint32_t len = sizeof(cmds) / sizeof(*cmds);
+
+		ret = i915_scheduler_queue_nonbatch(ring, cmds, len, &obj, 1, sched_flags);
+	} else {
+		uint32_t cmds[] = {
+			MI_DISPLAY_FLIP_I915 | plane_bit,
+			fb->pitches[0] | obj->tiling_mode,
+			intel_crtc->unpin_work->gtt_offset,
+			MI_NOOP
+		};
+		uint32_t len = sizeof(cmds) / sizeof(*cmds);
 
-	intel_ring_emit(ring, MI_DISPLAY_FLIP_I915 | plane_bit);
-	intel_ring_emit(ring, (fb->pitches[0] | obj->tiling_mode));
-	intel_ring_emit(ring, intel_crtc->unpin_work->gtt_offset);
-	intel_ring_emit(ring, (MI_NOOP));
+		ret = i915_scheduler_queue_nonbatch(ring, cmds, len, &obj, 1, sched_flags);
+	}
+	if (ret)
+		return ret;
 
 	intel_mark_page_flip_active(intel_crtc);
-	i915_add_request_wo_flush(ring);
+
 	return 0;
 }
 
-- 
1.7.9.5