[Intel-gfx] [PATCH v2 (rebased) 4/4] drm/i915: Add locking to pll updates, v2.

[Maarten Lankhorst]

With async modesets this is no longer protected with connection_mutex,
so ensure that each pll has its own lock. The pll configuration state
is still protected; it's only the pll updates that need locking against
concurrency.

Changes since v1:
- Rebased.
- Fix locking to protect all accesses. (Durgadoss)

Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_dpll_mgr.c | 25 +++++++++++++++++++------
 drivers/gpu/drm/i915/intel_dpll_mgr.h |  2 ++
 2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dpll_mgr.c b/drivers/gpu/drm/i915/intel_dpll_mgr.c
index a9084c7c3a36..e730b2001c07 100644
--- a/drivers/gpu/drm/i915/intel_dpll_mgr.c
+++ b/drivers/gpu/drm/i915/intel_dpll_mgr.c
@@ -89,14 +89,16 @@ void intel_prepare_shared_dpll(struct intel_crtc *crtc)
 	if (WARN_ON(pll == NULL))
 		return;
 
+	mutex_lock(&pll->lock);
 	WARN_ON(!pll->config.crtc_mask);
-	if (pll->active_mask == 0) {
+	if (!pll->active_mask) {
 		DRM_DEBUG_DRIVER("setting up %s\n", pll->name);
 		WARN_ON(pll->on);
 		assert_shared_dpll_disabled(dev_priv, pll);
 
 		pll->funcs.mode_set(dev_priv, pll);
 	}
+	mutex_unlock(&pll->lock);
 }
 
 /**
@@ -113,14 +115,17 @@ void intel_enable_shared_dpll(struct intel_crtc *crtc)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_shared_dpll *pll = crtc->config->shared_dpll;
 	unsigned crtc_mask = 1 << drm_crtc_index(&crtc->base);
-	unsigned old_mask = pll->active_mask;
+	unsigned old_mask;
 
 	if (WARN_ON(pll == NULL))
 		return;
 
+	mutex_lock(&pll->lock);
+	old_mask = pll->active_mask;
+
 	if (WARN_ON(!(pll->config.crtc_mask & crtc_mask)) ||
 	    WARN_ON(pll->active_mask & crtc_mask))
-		return;
+		goto out;
 
 	pll->active_mask |= crtc_mask;
 
@@ -131,13 +136,16 @@ void intel_enable_shared_dpll(struct intel_crtc *crtc)
 	if (old_mask) {
 		WARN_ON(!pll->on);
 		assert_shared_dpll_enabled(dev_priv, pll);
-		return;
+		goto out;
 	}
 	WARN_ON(pll->on);
 
 	DRM_DEBUG_KMS("enabling %s\n", pll->name);
 	pll->funcs.enable(dev_priv, pll);
 	pll->on = true;
+
+out:
+	mutex_unlock(&pll->lock);
 }
 
 void intel_disable_shared_dpll(struct intel_crtc *crtc)
@@ -154,8 +162,9 @@ void intel_disable_shared_dpll(struct intel_crtc *crtc)
 	if (pll == NULL)
 		return;
 
+	mutex_lock(&pll->lock);
 	if (WARN_ON(!(pll->active_mask & crtc_mask)))
-		return;
+		goto out;
 
 	DRM_DEBUG_KMS("disable %s (active %x, on? %d) for crtc %d\n",
 		      pll->name, pll->active_mask, pll->on,
@@ -166,11 +175,14 @@ void intel_disable_shared_dpll(struct intel_crtc *crtc)
 
 	pll->active_mask &= ~crtc_mask;
 	if (pll->active_mask)
-		return;
+		goto out;
 
 	DRM_DEBUG_KMS("disabling %s\n", pll->name);
 	pll->funcs.disable(dev_priv, pll);
 	pll->on = false;
+
+out:
+	mutex_unlock(&pll->lock);
 }
 
 static struct intel_shared_dpll *
@@ -1742,6 +1754,7 @@ void intel_shared_dpll_init(struct drm_device *dev)
 	for (i = 0; dpll_info[i].id >= 0; i++) {
 		WARN_ON(i != dpll_info[i].id);
 
+		mutex_init(&dev_priv->shared_dplls[i].lock);
 		dev_priv->shared_dplls[i].id = dpll_info[i].id;
 		dev_priv->shared_dplls[i].name = dpll_info[i].name;
 		dev_priv->shared_dplls[i].funcs = *dpll_info[i].funcs;
diff --git a/drivers/gpu/drm/i915/intel_dpll_mgr.h b/drivers/gpu/drm/i915/intel_dpll_mgr.h
index 89c5ada1a315..fba8cd36ce0a 100644
--- a/drivers/gpu/drm/i915/intel_dpll_mgr.h
+++ b/drivers/gpu/drm/i915/intel_dpll_mgr.h
@@ -113,6 +113,8 @@ struct intel_shared_dpll_funcs {
 };
 
 struct intel_shared_dpll {
+	struct mutex lock;
+
 	struct intel_shared_dpll_config config;
 
 	unsigned active_mask; /* mask of active CRTCs (i.e. DPMS on) */
-- 
2.1.0