[PATCH v2 3/3] ALSA: hda - implement a refcount for i915 power well switch

[mengdong.lin@intel.com]

From: Mengdong Lin <mengdong.lin@intel.com>

This is to check the refcount of audio driver and reduce calling to i915.

Signed-off-by: Mengdong Lin <mengdong.lin@intel.com>

diff --git a/sound/pci/hda/hda_i915.c b/sound/pci/hda/hda_i915.c
index 52a85d8..e831691 100644
--- a/sound/pci/hda/hda_i915.c
+++ b/sound/pci/hda/hda_i915.c
@@ -42,11 +42,16 @@ int hda_display_power(struct hda_intel *hda, bool enable)
 
 	dev_dbg(&hda->chip.pci->dev, "display power %s\n",
 		enable ? "enable" : "disable");
-	if (enable)
-		acomp->ops->get_power(acomp->dev);
-	else
-		acomp->ops->put_power(acomp->dev);
-
+	mutex_lock(&hda->display_power.lock);
+	if (enable) {
+		if (!hda->display_power.use_count++)
+			acomp->ops->get_power(acomp->dev);
+	} else {
+		WARN_ON(!hda->display_power.use_count);
+		if (!--hda->display_power.use_count)
+			acomp->ops->put_power(acomp->dev);
+	}
+	mutex_unlock(&hda->display_power.lock);
 	return 0;
 }
 
@@ -171,6 +176,8 @@ int hda_i915_init(struct hda_intel *hda)
 
 	dev_dbg(dev, "bound to i915 component master\n");
 
+	mutex_init(&hda->display_power.lock);
+
 	return 0;
 out_master_del:
 	component_master_del(dev, &hda_component_master_ops);
diff --git a/sound/pci/hda/hda_intel.h b/sound/pci/hda/hda_intel.h
index 2069898..3ca000a 100644
--- a/sound/pci/hda/hda_intel.h
+++ b/sound/pci/hda/hda_intel.h
@@ -19,6 +19,11 @@
 #include <drm/i915_component.h>
 #include "hda_controller.h"
 
+struct i915_display_power {
+	struct mutex lock;
+	int use_count;
+};
+
 struct hda_intel {
 	struct azx chip;
 
@@ -46,6 +51,7 @@ struct hda_intel {
 
 	/* i915 component interface */
 	struct i915_audio_component audio_component;
+	struct i915_display_power display_power;
 };
 
 #ifdef CONFIG_SND_HDA_I915
-- 
1.9.1