linux-kernel - [PATCH AUTOSEL 6.9 18/23] ALSA: ump: Set default protocol when not given explicitly

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Message-ID: <20240605120220.2966127-18-sashal@kernel.org>
Date: Wed,  5 Jun 2024 08:02:01 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Takashi Iwai <tiwai@...e.de>,
	Sasha Levin <sashal@...nel.org>,
	perex@...ex.cz,
	tiwai@...e.com,
	cujomalainey@...omium.org,
	linux-sound@...r.kernel.org
Subject: [PATCH AUTOSEL 6.9 18/23] ALSA: ump: Set default protocol when not given explicitly

From: Takashi Iwai <tiwai@...e.de>

[ Upstream commit bc42ca002d5d211f9c57334b9b4c25ddb0b4ec35 ]

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@...e.de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 sound/core/ump.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/sound/core/ump.c b/sound/core/ump.c
index fd6a68a542788..65980a2f4982f 100644
--- a/sound/core/ump.c
+++ b/sound/core/ump.c
@@ -960,6 +960,14 @@ 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);
-- 
2.43.0