ALSA: firewire/bebob: Add a workaround for M-Audio special Firewire series
In post commit, a quirk of this firmware about transactions is reported.
This commit apply a workaround for this quirk.
They often fail transactions due to gap_count mismatch. This state is changed
by generating bus reset.
The fw_schedule_bus_reset() is an exported symbol in firewire-core. But there
are no header for public. This commit moves its prototype from
drivers/firewire/core.h to include/linux/firewire.h.
This mismatch still affects bus management before generating this bus reset.
It still takes a time to call driver's probe() because transactions are still
often failed.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/firewire/bebob/bebob.c b/sound/firewire/bebob/bebob.c
index e1dd421..31b96b7 100644
--- a/sound/firewire/bebob/bebob.c
+++ b/sound/firewire/bebob/bebob.c
@@ -247,10 +247,26 @@
if (err < 0)
goto error;
- err = snd_card_register(card);
- if (err < 0) {
- snd_bebob_stream_destroy_duplex(bebob);
- goto error;
+ if (!bebob->maudio_special_quirk) {
+ err = snd_card_register(card);
+ if (err < 0) {
+ snd_bebob_stream_destroy_duplex(bebob);
+ goto error;
+ }
+ } else {
+ /*
+ * This is a workaround. This bus reset seems to have an effect
+ * to make devices correctly handling transactions. Without
+ * this, the devices have gap_count mismatch. This causes much
+ * failure of transaction.
+ *
+ * Just after registration, user-land application receive
+ * signals from dbus and starts I/Os. To avoid I/Os till the
+ * future bus reset, registration is done in next update().
+ */
+ bebob->deferred_registration = true;
+ fw_schedule_bus_reset(fw_parent_device(bebob->unit)->card,
+ false, true);
}
dev_set_drvdata(&unit->device, bebob);
@@ -273,6 +289,14 @@
fcp_bus_reset(bebob->unit);
snd_bebob_stream_update_duplex(bebob);
+
+ if (bebob->deferred_registration) {
+ if (snd_card_register(bebob->card) < 0) {
+ snd_bebob_stream_destroy_duplex(bebob);
+ snd_card_free(bebob->card);
+ }
+ bebob->deferred_registration = false;
+ }
}
static void bebob_remove(struct fw_unit *unit)