mirrors/linux
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2026-05-06 06:10:45 -04:00
Code Issues Packages Projects Releases Wiki Activity

ALSA: usb-audio: Accept multiple protocols in GTBs

Browse Source 
It's valid to give different protocols via multiple GTBs; e.g. a MIDI
1.0 port is embedded in a MIDI 2.0 device that talks with MIDI 2.0
protocol.  However, the current driver implementation assumes only a
single protocol over the whole Endpoint, and it can't handle such a
scenario.

This patch changes the driver's behavior to parse GTBs to accept
multiple protocols.  Instead of switching to the last given protocol,
it adds the protocol capability bits now.  Meanwhile, the default
protocol is chosen by the first given protocol in GTBs.

Practically seen, this should be a minor issue, as new devices should
specify the protocols properly via UMP Endpoint Info messages, so this
is rather just covering a corner case.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20240807092303.1935-3-tiwai@suse.de
This commit is contained in:
Takashi Iwai
2024-08-07 11:22:57 +02:00
parent 08713dcc49
commit b28654233f
1 changed files with 3 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
sound/usb/midi2.c
View File

@@ -607,12 +607,8 @@ static int parse_group_terminal_block(struct snd_usb_midi2_ump *rmidi,
return 0;
}
if (ump->info.protocol && ump->info.protocol != protocol)
usb_audio_info(rmidi->umidi->chip,
"Overriding preferred MIDI protocol in GTB %d: %x -> %x\n",
rmidi->usb_block_id, ump->info.protocol,
protocol);
ump->info.protocol = protocol;
if (!ump->info.protocol)
ump->info.protocol = protocol;
protocol_caps = protocol;
switch (desc->bMIDIProtocol) {
@@ -624,13 +620,7 @@ static int parse_group_terminal_block(struct snd_usb_midi2_ump *rmidi,
break;
}
if (ump->info.protocol_caps && ump->info.protocol_caps != protocol_caps)
usb_audio_info(rmidi->umidi->chip,
"Overriding MIDI protocol caps in GTB %d: %x -> %x\n",
rmidi->usb_block_id, ump->info.protocol_caps,
protocol_caps);
ump->info.protocol_caps = protocol_caps;
ump->info.protocol_caps |= protocol_caps;
return 0;
}