[PATCH 06/16] drm/i915: Add dev_priv->wm.mutex

[ville.syrjala@xxxxxxxxxxxxxxx]

From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>

Add a mutex to protect most of the watermark state. Will be useful when
we start to update watermarks asynchronously from plane updates, or
when we get finer grained locking for planes.

Reviewed-by: Paulo Zanoni <paulo.r.zanoni@xxxxxxxxx>
Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/i915/i915_drv.h  | 11 ++++++++++-
 drivers/gpu/drm/i915/intel_drv.h |  5 ++++-
 drivers/gpu/drm/i915/intel_pm.c  | 21 +++++++++++++++++++--
 3 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 459b02a..a2302a7 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1530,8 +1530,17 @@ struct drm_i915_private {
 		/* cursor */
 		uint16_t cur_latency[5];
 
-		/* current hardware state */
+		/*
+		 * current hardware state
+		 * protected by dev_priv->wm.mutex
+		 */
 		struct ilk_wm_values hw;
+
+		/*
+		 * protects some dev_priv->wm and intel_crtc->wm
+		 * state as well as the actual hardware registers
+		 */
+		struct mutex mutex;
 	} wm;
 
 	struct i915_runtime_pm pm;
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index d7c52b2..d75cc2b 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -404,7 +404,10 @@ struct intel_crtc {
 
 	/* per-pipe watermark state */
 	struct {
-		/* watermarks currently being used  */
+		/*
+		 * watermarks currently being used
+		 * protected by dev_priv->wm.mutex
+		 */
 		struct intel_pipe_wm active;
 	} wm;
 
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 2185553..2a63418 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -2743,8 +2743,13 @@ static void ilk_write_wm_values(struct drm_i915_private *dev_priv,
 static bool ilk_disable_lp_wm(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
+	bool changed;
+
+	mutex_lock(&dev_priv->wm.mutex);
+	changed = _ilk_disable_lp_wm(dev_priv, WM_DIRTY_LP_ALL);
+	mutex_unlock(&dev_priv->wm.mutex);
 
-	return _ilk_disable_lp_wm(dev_priv, WM_DIRTY_LP_ALL);
+	return changed;
 }
 
 static void ilk_program_watermarks(struct drm_device *dev)
@@ -2784,6 +2789,7 @@ static void ilk_update_wm(struct drm_crtc *crtc)
 {
 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
 	struct drm_device *dev = crtc->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct ilk_pipe_wm_parameters params = {};
 	struct intel_pipe_wm pipe_wm = {};
 
@@ -2791,12 +2797,17 @@ static void ilk_update_wm(struct drm_crtc *crtc)
 
 	intel_compute_pipe_wm(crtc, &params, &pipe_wm);
 
+	mutex_lock(&dev_priv->wm.mutex);
+
 	if (!memcmp(&intel_crtc->wm.active, &pipe_wm, sizeof(pipe_wm)))
-		return;
+		goto unlock;
 
 	intel_crtc->wm.active = pipe_wm;
 
 	ilk_program_watermarks(dev);
+
+ unlock:
+	mutex_unlock(&dev_priv->wm.mutex);
 }
 
 static void ilk_update_sprite_wm(struct drm_plane *plane,
@@ -2868,10 +2879,14 @@ void ilk_wm_get_hw_state(struct drm_device *dev)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_crtc *crtc;
 
+	mutex_lock(&dev_priv->wm.mutex);
+
 	_ilk_wm_get_hw_state(dev, &dev_priv->wm.hw);
 
 	for_each_crtc(dev, crtc)
 		_ilk_pipe_wm_hw_to_sw(crtc);
+
+	mutex_unlock(&dev_priv->wm.mutex);
 }
 
 /**
@@ -6369,6 +6384,8 @@ void intel_init_pm(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
+	mutex_init(&dev_priv->wm.mutex);
+
 	if (HAS_FBC(dev)) {
 		if (INTEL_INFO(dev)->gen >= 7) {
 			dev_priv->display.fbc_enabled = ironlake_fbc_enabled;
-- 
1.8.5.5

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