[PATCH 4/5] drm/i915: Add async page flip support for IVB

[Keith Packard]

This adds the necesary register defines for async page flipping
through the command ring, and then hooks those up for Ivybridge (gen7)
page flipping.

Signed-off-by: Keith Packard <keithp at keithp.com>
---
 drivers/gpu/drm/i915/i915_reg.h      |  6 ++++++
 drivers/gpu/drm/i915/intel_display.c | 40 ++++++++++++++++++++++++++++++++++--
 2 files changed, 44 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index dc3d6a7..029cfb0 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -209,6 +209,7 @@
 #define MI_LOAD_SCAN_LINES_INCL MI_INSTR(0x12, 0)
 #define MI_DISPLAY_FLIP		MI_INSTR(0x14, 2)
 #define MI_DISPLAY_FLIP_I915	MI_INSTR(0x14, 1)
+#define   MI_DISPLAY_FLIP_ASYNC_INDICATOR	(1 << 22)
 #define   MI_DISPLAY_FLIP_PLANE(n) ((n) << 20)
 /* IVB has funny definitions for which plane to flip. */
 #define   MI_DISPLAY_FLIP_IVB_PLANE_A  (0 << 19)
@@ -217,6 +218,11 @@
 #define   MI_DISPLAY_FLIP_IVB_SPRITE_B (3 << 19)
 #define   MI_DISPLAY_FLIP_IVB_PLANE_C  (4 << 19)
 #define   MI_DISPLAY_FLIP_IVB_SPRITE_C (5 << 19)
+/* These go in the bottom of the base address value */
+#define   MI_DISPLAY_FLIP_TYPE_SYNC    (0 << 0)
+#define   MI_DISPLAY_FLIP_TYPE_ASYNC   (1 << 0)
+#define   MI_DISPLAY_FLIP_TYPE_STEREO  (2 << 0)
+#define   MI_DISPLAY_FLIP_TYPE_SYNCHRONOUS	(0 << 0)
 #define MI_ARB_ON_OFF		MI_INSTR(0x08, 0)
 #define   MI_ARB_ENABLE			(1<<0)
 #define   MI_ARB_DISABLE		(0<<0)
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index bdb8854..1bcc6b4 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -7514,6 +7514,8 @@ static int intel_gen7_queue_flip(struct drm_device *dev,
 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
 	struct intel_ring_buffer *ring = &dev_priv->ring[BCS];
 	uint32_t plane_bit = 0;
+	uint32_t cmd;
+	uint32_t base;
 	int ret;
 
 	ret = intel_pin_and_fence_fb_obj(dev, obj, ring);
@@ -7536,13 +7538,43 @@ static int intel_gen7_queue_flip(struct drm_device *dev,
 		goto err_unpin;
 	}
 
+	cmd = MI_DISPLAY_FLIP_I915 | plane_bit;
+	base = i915_gem_obj_ggtt_offset(obj) + intel_crtc->dspaddr_offset;
+
+	if (flags & DRM_MODE_PAGE_FLIP_ASYNC) {
+
+		/* XXX check limitations for async flip here */
+
+		if (fb->pitches[0] != I915_READ(DSPSTRIDE(intel_crtc->plane))) {
+			WARN_ONCE(1, "mismatching stride in async plane flip (%d != %d)\n",
+				  fb->pitches[0], I915_READ(DSPSTRIDE(intel_crtc->plane)));
+			ret = -EINVAL;
+			goto err_unpin;
+		}
+
+		if (obj->tiling_mode != I915_TILING_X) {
+			WARN_ONCE(1, "async plane flip requires X tiling\n");
+			ret = -EINVAL;
+			goto err_unpin;
+		}
+
+		if ((I915_READ(DSPCNTR(intel_crtc->plane)) & DISPPLANE_TILED) == 0) {
+			WARN_ONCE(1, "display not currently tiled in async plane flip\n");
+			ret = -EINVAL;
+			goto err_unpin;
+		}
+		
+		cmd |= MI_DISPLAY_FLIP_ASYNC_INDICATOR;
+		base |= MI_DISPLAY_FLIP_TYPE_ASYNC;
+	}
+
 	ret = intel_ring_begin(ring, 4);
 	if (ret)
 		goto err_unpin;
 
-	intel_ring_emit(ring, MI_DISPLAY_FLIP_I915 | plane_bit);
+	intel_ring_emit(ring, cmd);
 	intel_ring_emit(ring, (fb->pitches[0] | obj->tiling_mode));
-	intel_ring_emit(ring, i915_gem_obj_ggtt_offset(obj) + intel_crtc->dspaddr_offset);
+	intel_ring_emit(ring, base);
 	intel_ring_emit(ring, (MI_NOOP));
 
 	intel_mark_page_flip_active(intel_crtc);
@@ -9705,6 +9737,10 @@ void intel_modeset_init(struct drm_device *dev)
 		dev->mode_config.max_width = 8192;
 		dev->mode_config.max_height = 8192;
 	}
+
+	if (IS_GEN7(dev))
+		dev->mode_config.async_page_flip = true;
+
 	dev->mode_config.fb_base = dev_priv->gtt.mappable_base;
 
 	DRM_DEBUG_KMS("%d display pipe%s available.\n",
-- 
1.8.3.2