jack alsa: optimize operation of reload request

do not close alsa devices that should stay open
do not prepare already prepared device
do not drop frames on device that is not running

Change-Id: Ibb6463bf6604a9e5e0038266bc99d2f8d838e135
Signed-off-by: Adam Miartus <amiartus@de.adit-jv.com>
(cherry picked from commit f5f8d29ef0)
Signed-off-by: Timo Wischer <twischer@de.adit-jv.com>

linux/alsa/alsa_driver.c

@@ -61,6 +61,7 @@ char* strcasestr(const char* haystack, const char* needle);
 
 static int alsa_driver_link (alsa_driver_t *driver);
 static int alsa_driver_open_device (alsa_driver_t *driver, alsa_device_t *device, bool is_capture);
+static int alsa_driver_get_state (snd_pcm_t *handle, int is_capture);
 
 void
 jack_driver_init (jack_driver_t *driver)
@@ -1520,20 +1521,22 @@ alsa_driver_start (alsa_driver_t *driver)
 			continue;
 		}
 
-		// TODO: amiartus, devices with target state PREPARED should also be prepared, however,
-		// this makes sense only if alsa_driver_stop alsa_driver_close do not close all devices
-		// as done in current implementation, once those functions are updated it makes sense to keep
-		// devices in PREPARED state so they can be started faster on Restart request
-		if (device->capture_target_state != SND_PCM_STATE_RUNNING) {
+		if (device->capture_target_state == SND_PCM_STATE_NOTREADY) {
 			continue;
 		}
 
-		driver->capture_nfds += snd_pcm_poll_descriptors_count (device->capture_handle);
+		if (device->capture_target_state == SND_PCM_STATE_RUNNING) {
+			driver->capture_nfds += snd_pcm_poll_descriptors_count (device->capture_handle);
+		}
 
 		if (group_done && device->capture_linked) {
 			continue;
 		}
 
+		if (alsa_driver_get_state(device->capture_handle, 1) == SND_PCM_STATE_PREPARED) {
+			continue;
+		}
+
 		if (device->capture_linked) {
 			group_done = 1;
 		}
@@ -1551,16 +1554,22 @@ alsa_driver_start (alsa_driver_t *driver)
 			continue;
 		}
 
-		if (device->playback_target_state != SND_PCM_STATE_RUNNING) {
+		if (device->playback_target_state == SND_PCM_STATE_NOTREADY) {
 			continue;
 		}
 
-		driver->playback_nfds += snd_pcm_poll_descriptors_count (device->playback_handle);
+		if (device->playback_target_state == SND_PCM_STATE_RUNNING) {
+			driver->playback_nfds += snd_pcm_poll_descriptors_count (device->playback_handle);
+		}
 
 		if (group_done && device->playback_linked) {
 			continue;
 		}
 
+		if (alsa_driver_get_state(device->playback_handle, 0) == SND_PCM_STATE_PREPARED) {
+			continue;
+		}
+
 		if (device->playback_linked) {
 			group_done = 1;
 		}
@@ -1754,6 +1763,10 @@ alsa_driver_stop (alsa_driver_t *driver)
 			continue;
 		}
 
+		if (alsa_driver_get_state(device->capture_handle, 1) != SND_PCM_STATE_RUNNING) {
+			continue;
+		}
+
 		if (device->capture_linked) {
 			group_done = 1;
 		}
@@ -1780,6 +1793,10 @@ alsa_driver_stop (alsa_driver_t *driver)
 			continue;
 		}
 
+		if (alsa_driver_get_state(device->playback_handle, 0) != SND_PCM_STATE_RUNNING) {
+			continue;
+		}
+
 		if (device->playback_linked) {
 			group_done = 1;
 		}
@@ -1821,6 +1838,10 @@ alsa_driver_close (alsa_driver_t *driver)
 			device->capture_linked = 0;
 		}
 
+		if (device->capture_target_state != SND_PCM_STATE_NOTREADY) {
+			continue;
+		}
+
 		snd_pcm_close(device->capture_handle);
 		device->capture_handle = NULL;
 	}
@@ -1836,6 +1857,10 @@ alsa_driver_close (alsa_driver_t *driver)
 			device->playback_linked = 0;
 		}
 
+		if (device->playback_target_state != SND_PCM_STATE_NOTREADY) {
+			continue;
+		}
+
 		snd_pcm_close(device->playback_handle);
 		device->playback_handle = NULL;
 	}