[alsa-devel] [RFC PATCH] ALSA: hda - suspend codecs in parallel

[mengdong.lin at intel.com]

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

The time to suspend a single codec may be several hundreds of ms. When runtime
power saving is not enabled, driver suspend time can be long especially there
are more than one codec on the bus.

To reduce driver suspend time, this patch creates a work queue for each codec
and will suspend the codecs in parallel, if there are multiple codecs on bus.

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

diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c
index cb0c776..c9092a1 100644
--- a/sound/pci/hda/hda_codec.c
+++ b/sound/pci/hda/hda_codec.c
@@ -97,6 +97,7 @@ EXPORT_SYMBOL_HDA(snd_hda_delete_codec_preset);
 #ifdef CONFIG_PM
 #define codec_in_pm(codec)	((codec)->in_pm)
 static void hda_power_work(struct work_struct *work);
+static void hda_pm_work(struct work_struct *work);
 static void hda_keep_power_on(struct hda_codec *codec);
 #define hda_codec_is_power_on(codec)	((codec)->power_on)
 static inline void hda_call_pm_notify(struct hda_bus *bus, bool power_up)
@@ -1355,6 +1356,8 @@ static void snd_hda_codec_free(struct hda_codec *codec)
 #ifdef CONFIG_PM
 	if (!codec->pm_down_notified) /* cancel leftover refcounts */
 		hda_call_pm_notify(codec->bus, false);
+	if (codec->pm_wq)
+		destroy_workqueue(codec->pm_wq);
 #endif
 	module_put(codec->owner);
 	free_hda_cache(&codec->amp_cache);
@@ -1434,6 +1437,13 @@ int snd_hda_codec_new(struct hda_bus *bus,
 	 */
 	hda_keep_power_on(codec);
 	hda_call_pm_notify(bus, true);
+
+	codec->pm_wq = create_workqueue("hda_codec_wq");
+	if (!codec->pm_wq) {
+		snd_hda_codec_free(codec);
+		return -ENOMEM;
+	}
+	INIT_WORK(&codec->pm_work, hda_pm_work);
 #endif
 
 	if (codec->bus->modelname) {
@@ -1445,6 +1455,7 @@ int snd_hda_codec_new(struct hda_bus *bus,
 	}
 
 	list_add_tail(&codec->list, &bus->codec_list);
+	bus->num_codecs++;
 	bus->caddr_tbl[codec_addr] = codec;
 
 	codec->vendor_id = snd_hda_param_read(codec, AC_NODE_ROOT,
@@ -5032,6 +5043,14 @@ int snd_hda_check_amp_list_power(struct hda_codec *codec,
 	return 0;
 }
 EXPORT_SYMBOL_HDA(snd_hda_check_amp_list_power);
+
+static void hda_pm_work(struct work_struct *work)
+{
+	struct hda_codec *codec =
+		container_of(work, struct hda_codec, pm_work);
+
+	hda_call_codec_suspend(codec, false);
+}
 #endif
 
 /*
@@ -5595,11 +5614,24 @@ EXPORT_SYMBOL_HDA(snd_hda_add_imux_item);
 int snd_hda_suspend(struct hda_bus *bus)
 {
 	struct hda_codec *codec;
+	unsigned int mask = 0;
 
 	list_for_each_entry(codec, &bus->codec_list, list) {
 		cancel_delayed_work_sync(&codec->jackpoll_work);
-		if (hda_codec_is_power_on(codec))
-			hda_call_codec_suspend(codec, false);
+		if (hda_codec_is_power_on(codec)) {
+			if (codec->epss || bus->num_codecs == 1)
+				hda_call_codec_suspend(codec, false);
+			else {
+				mask |= 1 << codec->addr;
+				queue_work(codec->pm_wq, &codec->pm_work);
+			}
+		}
+	}
+
+	list_for_each_entry(codec, &bus->codec_list, list) {
+		if (mask & (1 << codec->addr))
+			flush_work(&codec->pm_work);
+
 	}
 	return 0;
 }
diff --git a/sound/pci/hda/hda_codec.h b/sound/pci/hda/hda_codec.h
index 7aa9870..ffb1866 100644
--- a/sound/pci/hda/hda_codec.h
+++ b/sound/pci/hda/hda_codec.h
@@ -673,6 +673,7 @@ struct hda_bus {
 
 	/* codec linked list */
 	struct list_head codec_list;
+	unsigned int num_codecs;
 	/* link caddr -> codec */
 	struct hda_codec *caddr_tbl[HDA_MAX_CODEC_ADDRESS + 1];
 
@@ -916,6 +917,8 @@ struct hda_codec {
 	unsigned long power_off_acct;
 	unsigned long power_jiffies;
 	spinlock_t power_lock;
+	struct workqueue_struct  *pm_wq;
+	struct work_struct pm_work;
 #endif
 
 	/* filter the requested power state per nid */
-- 
1.8.1.2