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Diffstat (limited to 'sound/firewire/bebob/bebob.c')
-rw-r--r--sound/firewire/bebob/bebob.c20
1 files changed, 16 insertions, 4 deletions
diff --git a/sound/firewire/bebob/bebob.c b/sound/firewire/bebob/bebob.c
index 671179eaff1e..3e4e0756e3fe 100644
--- a/sound/firewire/bebob/bebob.c
+++ b/sound/firewire/bebob/bebob.c
@@ -300,6 +300,22 @@ error:
return err;
}
+/*
+ * This driver doesn't update streams in bus reset handler.
+ *
+ * DM1000/ DM1100/DM1500 chipsets with BeBoB firmware transfer packets with
+ * discontinued counter at bus reset. This discontinuity is immediately
+ * detected in packet streaming layer, then it sets XRUN to PCM substream.
+ *
+ * ALSA PCM applications can know the XRUN by getting -EPIPE from PCM operation.
+ * Then, they can recover the PCM substream by executing ioctl(2) with
+ * SNDRV_PCM_IOCTL_PREPARE. 'struct snd_pcm_ops.prepare' is called and drivers
+ * restart packet streaming.
+ *
+ * The above processing may be executed before this bus-reset handler is
+ * executed. When this handler updates streams with current isochronous
+ * channels, the streams already have the current ones.
+ */
static void
bebob_update(struct fw_unit *unit)
{
@@ -310,10 +326,6 @@ bebob_update(struct fw_unit *unit)
fcp_bus_reset(bebob->unit);
- mutex_lock(&bebob->mutex);
- snd_bebob_stream_update_duplex(bebob);
- mutex_unlock(&bebob->mutex);
-
if (bebob->deferred_registration) {
if (snd_card_register(bebob->card) < 0) {
snd_bebob_stream_destroy_duplex(bebob);