bluez5: remove mtu hardcoding

Hardcoding MTU is no longer necessary with the reworked SCO i/o, which
guesses suitable write sizes based on rx.

spa/plugins/bluez5/backend-hsp-native.c

@@ -234,10 +234,12 @@ static int sco_acquire_cb(void *data, bool optional)
 		goto fail;
 
 	t->fd = sock;
+
+	/* Fallback value */
 	t->read_mtu = 48;
 	t->write_mtu = 48;
 
-	if (false) {
+	if (true) {
 		struct sco_options sco_opt;
 
 		len = sizeof(sco_opt);

spa/plugins/bluez5/backend-hsphfpd.c

@@ -56,7 +56,6 @@ struct spa_bt_backend {
 
 	unsigned int filters_added:1;
 	unsigned int msbc_supported:1;
-	int msbc_force_mtu;
 };
 
 enum hsphfpd_volume_control {
@@ -713,27 +712,9 @@ static DBusHandlerResult hsphfpd_new_audio_connection(DBusConnection *conn, DBus
 	pa_hook_fire(pa_bluetooth_discovery_hook(hsphfpd->discovery, PA_BLUETOOTH_HOOK_TRANSPORT_TX_VOLUME_GAIN_CHANGED), transport);
 #endif
 
-	if (transport->codec == HFP_AUDIO_CODEC_CVSD) {
-		transport->read_mtu = 48;
-		transport->write_mtu = 48;
-	} else if (transport->codec == HFP_AUDIO_CODEC_MSBC && backend->msbc_force_mtu != 0) {
-		transport->read_mtu = mtu;
-
-		/* Force low write packet size, as kernel (at least <= 5.9) does not
-		 * provide correct values for userspace. The value 24 should be
-		 * right for bluetooth ALT1 mode. See
-		 * https://lore.kernel.org/linux-bluetooth/20201210003528.3pmaxvubiwegxmhl@pali/T/
-		 *
-		 * XXX: revise when hsphfpd/kernel reports correct numbers
-		 */
-		transport->write_mtu = (backend->msbc_force_mtu > 0) ? backend->msbc_force_mtu : 24;
-		spa_log_warn(backend->log, "hsphfpd: forcing write_mtu = %d for mSBC; "
-			     "set bluez5.msbc-force-mtu=0 to use autodetected (%d)",
-			     (int) transport->write_mtu, (int) mtu);
-	} else {
 	transport->read_mtu = mtu;
 	transport->write_mtu = mtu;
-	}
+
 	transport->fd = fd;
 
 	if ((r = dbus_message_new_method_return(m)) == NULL)
@@ -1507,10 +1488,6 @@ struct spa_bt_backend *backend_hsphfpd_new(struct spa_bt_monitor *monitor,
 		backend->msbc_supported = strcmp(str, "true") == 0 || atoi(str) == 1;
 	else
 		backend->msbc_supported = false;
-	if (info && (str = spa_dict_lookup(info, "bluez5.msbc-force-mtu")))
-		backend->msbc_force_mtu = atoi(str);
-	else
-		backend->msbc_force_mtu = -1;
 
 	spa_list_init(&backend->endpoint_list);
 

spa/plugins/bluez5/backend-ofono.c

@@ -51,7 +51,6 @@ struct spa_bt_backend {
 
 	unsigned int filters_added:1;
 	unsigned int msbc_supported:1;
-	int msbc_force_mtu;
 };
 
 #define OFONO_SERVICE "org.ofono"
@@ -85,13 +84,13 @@ struct spa_bt_backend {
 
 static void ofono_transport_get_mtu(struct spa_bt_backend *backend, struct spa_bt_transport *t)
 {
-	if (t->codec == HFP_AUDIO_CODEC_CVSD) {
-		t->read_mtu = 48;
-		t->write_mtu = 48;
-	} else {
 	struct sco_options sco_opt;
 	socklen_t len;
 
+	/* Fallback values */
+	t->read_mtu = 48;
+	t->write_mtu = 48;
+
 	len = sizeof(sco_opt);
 	memset(&sco_opt, 0, len);
 
@@ -102,21 +101,6 @@ static void ofono_transport_get_mtu(struct spa_bt_backend *backend, struct spa_b
 		t->read_mtu = sco_opt.mtu;
 		t->write_mtu = sco_opt.mtu;
 	}
-
-		if (backend->msbc_force_mtu != 0 && t->codec == HFP_AUDIO_CODEC_MSBC) {
-			/* Force low write packet size, as kernel (at least <= 5.9) does not
-			 * provide correct values for userspace. The value 24 should be
-			 * right for bluetooth ALT1 mode. See
-			 * https://lore.kernel.org/linux-bluetooth/20201210003528.3pmaxvubiwegxmhl@pali/T/
-			 *
-			 * XXX: revise when kernel reports correct numbers
-			 */
-			t->write_mtu = (backend->msbc_force_mtu > 0) ? backend->msbc_force_mtu : 24;
-			spa_log_warn(backend->log, NAME": forcing write_mtu = %d for mSBC; "
-				     "set bluez5.msbc-force-mtu=0 to autodetect",
-				     (int) t->write_mtu);
-		}
-	}
 }
 
 static struct spa_bt_transport *_transport_create(struct spa_bt_backend *backend,
@@ -719,10 +703,6 @@ struct spa_bt_backend *backend_ofono_new(struct spa_bt_monitor *monitor,
 		backend->msbc_supported = strcmp(str, "true") == 0 || atoi(str) == 1;
 	else
 		backend->msbc_supported = false;
-	if (info && (str = spa_dict_lookup(info, "bluez5.msbc-force-mtu")))
-		backend->msbc_force_mtu = atoi(str);
-	else
-		backend->msbc_force_mtu = -1;
 
 	if (!dbus_connection_register_object_path(backend->conn,
 						  OFONO_AUDIO_CLIENT,