commit c30076568d20bd6f7a4e021b19672a6b03266430
author Takashi Sakamoto <o-takashi@sakamocchi.jp> Mon Feb 08 22:54:18 2016 +0900
committer Takashi Iwai <tiwai@suse.de> Tue Feb 09 12:22:10 2016 +0100
tree d62eab25502ccdf81ccd4934e009c09b4fcd77db
parent b9022f4d2cb4660249036768f7d09442b213d12f

ALSA: dice: get the number of MBLA data channel at opening PCM substream

This commit is a preparation to remove members related to channel cache
for the number of channels for multi bit linear audio data and MIDI
ports. This commit changes the way to get the number of multi bit linear
audio data channel. It's directly retrieved by asynchronous transactions
to some registers.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/firewire/dice/dice-pcm.c

diff --git a/sound/firewire/dice/dice-pcm.c b/sound/firewire/dice/dice-pcm.c
index 0b6e6bb..a5c9b58 100644
--- a/sound/firewire/dice/dice-pcm.c
+++ b/sound/firewire/dice/dice-pcm.c
@@ -294,17 +294,30 @@
 		.page      = snd_pcm_lib_get_vmalloc_page,
 		.mmap      = snd_pcm_lib_mmap_vmalloc,
 	};
+	__be32 reg;
 	struct snd_pcm *pcm;
-	unsigned int i, capture, playback;
+	unsigned int capture, playback;
 	int err;
 
-	capture = playback = 0;
-	for (i = 0; i < 3; i++) {
-		if (dice->tx_channels[i] > 0)
-			capture = 1;
-		if (dice->rx_channels[i] > 0)
-			playback = 1;
-	}
+	/*
+	 * Check whether PCM substreams are required.
+	 *
+	 * TODO: in the case that any PCM substreams are not avail at a certain
+	 * sampling transfer frequency?
+	 */
+	err = snd_dice_transaction_read_tx(dice, TX_NUMBER_AUDIO,
+					   &reg, sizeof(reg));
+	if (err < 0)
+		return err;
+	if (be32_to_cpu(reg) > 0)
+		capture = 1;
+
+	err = snd_dice_transaction_read_rx(dice, RX_NUMBER_AUDIO,
+					   &reg, sizeof(reg));
+	if (err < 0)
+		return err;
+	if (be32_to_cpu(reg) > 0)
+		playback = 1;
 
 	err = snd_pcm_new(dice->card, "DICE", 0, playback, capture, &pcm);
 	if (err < 0)