staging: line6: separate handling of buffer allocation and stream startup

There are several features of the Line6 USB driver which require PCM
data to be exchanged with the device:
*) PCM playback and capture via ALSA
*) software monitoring (for devices without hardware monitoring)
*) optional impulse response measurement
However, from the device's point of view, there is just a single
capture and playback stream, which must be shared between these
subsystems. It is therefore necessary to maintain the state of the
subsystems with respect to PCM usage. We define several constants of
the form LINE6_BIT_PCM_<subsystem>_<direction>_<resource> with the
following meanings:
*) <subsystem> is one of
-) ALSA: PCM playback and capture via ALSA
-) MONITOR: software monitoring
-) IMPULSE: optional impulse response measurement
*) <direction> is one of
-) PLAYBACK: audio output (from host to device)
-) CAPTURE: audio input (from device to host)
*) <resource> is one of
-) BUFFER: buffer required by PCM data stream
-) STREAM: actual PCM data stream

The subsystems call line6_pcm_acquire() to acquire the (shared)
resources needed for a particular operation (e.g., allocate the buffer
for ALSA playback or start the capture stream for software monitoring).
When a resource is no longer needed, it is released by calling
line6_pcm_release(). Buffer allocation and stream startup are handled
separately to allow the ALSA kernel driver to perform them at
appropriate places (since the callback which starts a PCM stream is not
allowed to sleep).

Signed-off-by: Markus Grabner <grabner@icg.tugraz.at>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 4 insertions, 4 deletions

diff --git a/drivers/staging/line6/toneport.c b/drivers/staging/line6/toneport.c
index b776130058ca..b754f69a29c4 100644
--- a/drivers/staging/line6/toneport.c
+++ b/drivers/staging/line6/toneport.c
@@ -207,9 +207,9 @@ static int snd_toneport_monitor_put(struct snd_kcontrol *kcontrol,
 	line6pcm->volume_monitor = ucontrol->value.integer.value[0];
 
 	if (line6pcm->volume_monitor > 0)
-		line6_pcm_start(line6pcm, MASK_PCM_MONITOR);
+		line6_pcm_acquire(line6pcm, LINE6_BITS_PCM_MONITOR);
 	else
-		line6_pcm_stop(line6pcm, MASK_PCM_MONITOR);
+		line6_pcm_release(line6pcm, LINE6_BITS_PCM_MONITOR);
 
 	return 1;
 }
@@ -264,7 +264,7 @@ static void toneport_start_pcm(unsigned long arg)
 {
 	struct usb_line6_toneport *toneport = (struct usb_line6_toneport *)arg;
 	struct usb_line6 *line6 = &toneport->line6;
-	line6_pcm_start(line6->line6pcm, MASK_PCM_MONITOR);
+	line6_pcm_acquire(line6->line6pcm, LINE6_BITS_PCM_MONITOR);
 }
 
 /* control definition */
@@ -446,7 +446,7 @@ void line6_toneport_disconnect(struct usb_interface *interface)
 		struct snd_line6_pcm *line6pcm = toneport->line6.line6pcm;
 
 		if (line6pcm != NULL) {
-			line6_pcm_stop(line6pcm, MASK_PCM_MONITOR);
+			line6_pcm_release(line6pcm, LINE6_BITS_PCM_MONITOR);
 			line6_pcm_disconnect(line6pcm);
 		}
 	}