[PATCH 3/3] drm/i915: track sprite coverage and disable primary plane if possible

[Jesse Barnes <jbarnes@virtuousgeek.org>]

To save power when the sprite is full screen, we can disable the primary
plane on the same pipe.  Track the sprite status and enable/disable the
primary opportunistically.

v2: remove primary plane enable/disable hooks; they're identical

Signed-off-by: Jesse Barnes
---
 drivers/gpu/drm/i915/intel_drv.h    |    1 +
 drivers/gpu/drm/i915/intel_sprite.c |   41 +++++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index e0407cd..0340b4c 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -180,6 +180,7 @@ struct intel_plane {
 	struct drm_plane base;
 	enum pipe pipe;
 	struct drm_i915_gem_object *obj;
+	bool primary_disabled;
 	int max_downscale;
 	u32 lut_r[1024], lut_g[1024], lut_b[1024];
 	void (*update_plane)(struct drm_plane *plane,
diff --git a/drivers/gpu/drm/i915/intel_sprite.c b/drivers/gpu/drm/i915/intel_sprite.c
index a51edc9..976eee3 100644
--- a/drivers/gpu/drm/i915/intel_sprite.c
+++ b/drivers/gpu/drm/i915/intel_sprite.c
@@ -329,6 +329,28 @@ snb_get_destkey(struct drm_plane *plane)
 	return value;
 }
 
+static void
+intel_enable_primary(struct drm_crtc *crtc)
+{
+	struct drm_device *dev = crtc->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
+	int reg = DSPCNTR(intel_crtc->plane);
+
+	I915_WRITE(reg, I915_READ(reg) | DISPLAY_PLANE_ENABLE);
+}
+
+static void
+intel_disable_primary(struct drm_crtc *crtc)
+{
+	struct drm_device *dev = crtc->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
+	int reg = DSPCNTR(intel_crtc->plane);
+
+	I915_WRITE(reg, I915_READ(reg) & ~DISPLAY_PLANE_ENABLE);
+}
+
 static int
 intel_update_plane(struct drm_plane *plane, struct drm_crtc *crtc,
 		   struct drm_framebuffer *fb, int crtc_x, int crtc_y,
@@ -415,9 +437,23 @@ intel_update_plane(struct drm_plane *plane, struct drm_crtc *crtc,
 
 	intel_plane->obj = obj;
 
+	/*
+	 * Be sure to re-enable the primary before the sprite is no longer
+	 * covering it fully.
+	 */
+	if (!disable_primary && intel_plane->primary_disabled) {
+		intel_enable_primary(crtc);
+		intel_plane->primary_disabled = false;
+	}
+
 	intel_plane->update_plane(plane, fb, obj, crtc_x, crtc_y,
 				  crtc_w, crtc_h, x, y, src_w, src_h);
 
+	if (disable_primary) {
+		intel_disable_primary(crtc);
+		intel_plane->primary_disabled = true;
+	}
+
 	/* Unpin old obj after new one is active to avoid ugliness */
 	if (old_obj) {
 		/*
@@ -447,6 +483,11 @@ intel_disable_plane(struct drm_plane *plane)
 	struct intel_plane *intel_plane = to_intel_plane(plane);
 	int ret = 0;
 
+	if (intel_plane->primary_disabled) {
+		intel_enable_primary(plane->crtc);
+		intel_plane->primary_disabled = false;
+	}
+
 	intel_plane->disable_plane(plane);
 
 	if (!intel_plane->obj)
-- 
1.7.4.1