From 2e4c9ab2574eeaa7b893c7d35b4a9f60fd681ddd Mon Sep 17 00:00:00 2001 From: Nicholas Hobson Date: Sat, 12 Sep 2026 03:28:42 +0000 Subject: [PATCH] ALSA: usb-audio: keep MIDI input running for Roland TD-11 The TD-11 hands MIDI handling off to the host once connected via USB. If no MIDI input port is opened on the host, the device itself becomes unusable as a standalone instrument until its input is serviced, independent of anything happening on the computer. Add a per-device keep_input_running flag, set for the TD-11 in snd_usbmidi_detect_roland(), and check it alongside the existing opened[1] check in snd_usbmidi_input_start()/snd_usbmidi_input_stop() so that input is started at device creation and never stopped for these devices, regardless of whether a client has the input port open. Signed-off-by: Nicholas Hobson Link: https://patch.msgid.link/MN2PR15MB3472557AF39DC3A4CA9E753FF8BD2@MN2PR15MB3472.namprd15.prod.outlook.com Signed-off-by: Takashi Iwai --- sound/usb/midi.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/sound/usb/midi.c b/sound/usb/midi.c index 8a9bc37f0b6e..be2b178d13d6 100644 --- a/sound/usb/midi.c +++ b/sound/usb/midi.c @@ -113,6 +113,7 @@ struct snd_usb_midi { unsigned int opened[2]; unsigned char disconnected; unsigned char input_running; + unsigned char keep_input_running; struct snd_kcontrol *roland_load_ctl; }; @@ -1170,7 +1171,7 @@ static int substream_open(struct snd_rawmidi_substream *substream, int dir, snd_usbmidi_input_start(&umidi->list); } else { umidi->opened[dir]--; - if (!umidi->opened[1]) + if (!umidi->opened[1] && !umidi->keep_input_running) snd_usbmidi_input_stop(&umidi->list); if (!umidi->opened[0] && !umidi->opened[1]) { if (umidi->roland_load_ctl) { @@ -2260,6 +2261,10 @@ static int snd_usbmidi_detect_roland(struct snd_usb_midi *umidi, struct usb_host_interface *hostif; u8 *cs_desc; + /* TD-11 becomes unusable if input isn't serviced continuously */ + if (umidi->usb_id == USB_ID(0x0582, 0x0151)) + umidi->keep_input_running = 1; + intf = umidi->iface; if (!intf) return -ENOENT; @@ -2467,7 +2472,7 @@ void snd_usbmidi_input_start(struct list_head *p) int i; umidi = list_entry(p, struct snd_usb_midi, list); - if (umidi->input_running || !umidi->opened[1]) + if (umidi->input_running || (!umidi->opened[1] && !umidi->keep_input_running)) return; for (i = 0; i < MIDI_MAX_ENDPOINTS; ++i) snd_usbmidi_input_start_ep(umidi, umidi->endpoints[i].in); @@ -2642,6 +2647,10 @@ int __snd_usbmidi_create(struct snd_card *card, if (err < 0) goto exit; + /* start input for devices that need continuous servicing */ + if (umidi->keep_input_running) + snd_usbmidi_input_start(&umidi->list); + usb_autopm_get_interface_no_resume(umidi->iface); list_add_tail(&umidi->list, midi_list);