ALSA: bebob: fix rx packet format for Yamaha GO44/GO46, Terratec Phase 24/x24

Below devices reports zero as the number of channels for external output
plug with MIDI type:

 * Yamaha GO44/GO46
 * Terratec Phase 24/X24

As a result, rx packet format is invalid and they generate silent sound.
This is a regression added in v5.13.

This commit fixes the bug, addressed at a commit 1bd1b3be8655 ("ALSA:
bebob: perform sequence replay for media clock recovery").

Cc: <stable@vger.kernel.org>
Fixes: 5c6ea94f2b7c ("ALSA: bebob: detect the number of available MIDI ports")
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20210618040447.113306-1-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/firewire/bebob/bebob_stream.c b/sound/firewire/bebob/bebob_stream.c
index e3e23e4..8629b14 100644 (file)
--- a/sound/firewire/bebob/bebob_stream.c
+++ b/sound/firewire/bebob/bebob_stream.c
@@ -856,6 +856,11 @@ static int detect_midi_ports(struct snd_bebob *bebob,
                err = avc_bridgeco_get_plug_ch_count(bebob->unit, addr, &ch_count);
                if (err < 0)
                        break;
+               // Yamaha GO44, GO46, Terratec Phase 24, Phase x24 reports 0 for the number of
+               // channels in external output plug 3 (MIDI type) even if it has a pair of physical
+               // MIDI jacks. As a workaround, assume it as one.
+               if (ch_count == 0)
+                       ch_count = 1;
                *midi_ports += ch_count;
        }
 
@@ -934,12 +939,12 @@ int snd_bebob_stream_discover(struct snd_bebob *bebob)
        if (err < 0)
                goto end;
 
-       err = detect_midi_ports(bebob, bebob->rx_stream_formations, addr, AVC_BRIDGECO_PLUG_DIR_IN,
+       err = detect_midi_ports(bebob, bebob->tx_stream_formations, addr, AVC_BRIDGECO_PLUG_DIR_IN,
                                plugs[2], &bebob->midi_input_ports);
        if (err < 0)
                goto end;
 
-       err = detect_midi_ports(bebob, bebob->tx_stream_formations, addr, AVC_BRIDGECO_PLUG_DIR_OUT,
+       err = detect_midi_ports(bebob, bebob->rx_stream_formations, addr, AVC_BRIDGECO_PLUG_DIR_OUT,
                                plugs[3], &bebob->midi_output_ports);
        if (err < 0)
                goto end;