ALSA: ump: Set default protocol when not given explicitly

When an inquiry of the current protocol via UMP Stream Configuration
message fails by some reason, we may leave the current protocol
undefined, which may lead to unexpected behavior.  Better to assume a
valid protocol found in the protocol capability bits instead.

For a device that doesn't support the UMP v1.2 feature, it won't reach
to this code path, and USB MIDI GTB descriptor would be used for
determining the protocol, instead.

Link: https://lore.kernel.org/r/20240529164723.18309-2-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/core/ump.c b/sound/core/ump.c
index 117c7ecc48563b35792556510d5ca6583e696fc6..3f61220c23b4ec028faddd63bff776a91cc8067c 100644 (file)
--- a/sound/core/ump.c
+++ b/sound/core/ump.c
@@ -967,6 +967,14 @@ int snd_ump_parse_endpoint(struct snd_ump_endpoint *ump)
        if (err < 0)
                ump_dbg(ump, "Unable to get UMP EP stream config\n");
 
+       /* If no protocol is set by some reason, assume the valid one */
+       if (!(ump->info.protocol & SNDRV_UMP_EP_INFO_PROTO_MIDI_MASK)) {
+               if (ump->info.protocol_caps & SNDRV_UMP_EP_INFO_PROTO_MIDI2)
+                       ump->info.protocol |= SNDRV_UMP_EP_INFO_PROTO_MIDI2;
+               else if (ump->info.protocol_caps & SNDRV_UMP_EP_INFO_PROTO_MIDI1)
+                       ump->info.protocol |= SNDRV_UMP_EP_INFO_PROTO_MIDI1;
+       }
+
        /* Query and create blocks from Function Blocks */
        for (blk = 0; blk < ump->info.num_blocks; blk++) {
                err = create_block_from_fb_info(ump, blk);