[Intel-gfx] [PATCH 14/24] drm/i915: Add dev_priv->wm.mutex

[ville.syrjala at linux.intel.com]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

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.

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 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 29da39f..0b19723 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1595,8 +1595,17 @@ typedef 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_package_c8 pc8;
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index f022a78..8e32d69 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -384,7 +384,10 @@ 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 3f5c1dc..d8adcb3 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -2692,8 +2692,13 @@ 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;
 
-	return _ilk_disable_lp_wm(dev_priv, WM_DIRTY_LP_ALL);
+	mutex_lock(&dev_priv->wm.mutex);
+	changed = _ilk_disable_lp_wm(dev_priv, WM_DIRTY_LP_ALL);
+	mutex_unlock(&dev_priv->wm.mutex);
+
+	return changed;
 }
 
 static void ilk_program_watermarks(struct drm_device *dev)
@@ -2733,6 +2738,7 @@ 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 = {};
 
@@ -2740,12 +2746,17 @@ 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,
@@ -2817,10 +2828,14 @@ 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);
 
 	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head)
 		_ilk_pipe_wm_hw_to_sw(crtc);
+
+	mutex_unlock(&dev_priv->wm.mutex);
 }
 
 /**
@@ -5760,6 +5775,8 @@ 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;
-- 
1.8.3.2