ALSA: ump: Handle MIDI 1.0 Function Block in MIDI 2.0 protocol

The UMP v1.1 spec says in the section 6.2.1:
"If a UMP Endpoint declares MIDI 2.0 Protocol but a Function Block
represents a MIDI 1.0 connection, then may optionally be used for
messages to/from that Function Block."

It implies that the driver can (and should) keep MIDI 1.0 CVM
exceptionally for those FBs even if UMP Endpoint is running in MIDI
2.0 protocol, and the current driver lacks of it.

This patch extends the sequencer port info to indicate a MIDI 1.0
port, and tries to send/receive MIDI 1.0 CVM as is when this port is
the source or sink.  The sequencer port flag is set by the driver at
parsing FBs and GTBs although application can set it to its own
user-space clients, too.

Link: https://patch.msgid.link/20240806070024.14301-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 9 insertions, 1 deletions

diff --git a/sound/core/ump.c b/sound/core/ump.c
index e39e9cda4912..c7c3581bbbbc 100644
--- a/sound/core/ump.c
+++ b/sound/core/ump.c
@@ -538,6 +538,7 @@ static void update_group_attrs(struct snd_ump_endpoint *ump)
 		group->active = 0;
 		group->group = i;
 		group->valid = false;
+		group->is_midi1 = false;
 	}
 
 	list_for_each_entry(fb, &ump->block_list, list) {
@@ -548,6 +549,8 @@ static void update_group_attrs(struct snd_ump_endpoint *ump)
 			group->valid = true;
 			if (fb->info.active)
 				group->active = 1;
+			if (fb->info.flags & SNDRV_UMP_BLOCK_IS_MIDI1)
+				group->is_midi1 = true;
 			switch (fb->info.direction) {
 			case SNDRV_UMP_DIR_INPUT:
 				group->dir_bits |= (1 << SNDRV_RAWMIDI_STREAM_INPUT);
@@ -1156,6 +1159,7 @@ static int process_legacy_output(struct snd_ump_endpoint *ump,
 	struct snd_rawmidi_substream *substream;
 	struct ump_cvt_to_ump *ctx;
 	const int dir = SNDRV_RAWMIDI_STREAM_OUTPUT;
+	unsigned int protocol;
 	unsigned char c;
 	int group, size = 0;
 
@@ -1168,9 +1172,13 @@ static int process_legacy_output(struct snd_ump_endpoint *ump,
 		if (!substream)
 			continue;
 		ctx = &ump->out_cvts[group];
+		protocol = ump->info.protocol;
+		if ((protocol & SNDRV_UMP_EP_INFO_PROTO_MIDI2) &&
+		    ump->groups[group].is_midi1)
+			protocol = SNDRV_UMP_EP_INFO_PROTO_MIDI1;
 		while (!ctx->ump_bytes &&
 		       snd_rawmidi_transmit(substream, &c, 1) > 0)
-			snd_ump_convert_to_ump(ctx, group, ump->info.protocol, c);
+			snd_ump_convert_to_ump(ctx, group, protocol, c);
 		if (ctx->ump_bytes && ctx->ump_bytes <= count) {
 			size = ctx->ump_bytes;
 			memcpy(buffer, ctx->ump, size);