From a79807683781d3f215e9d958494e52ed70f4ad27 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Wed, 21 Jun 2023 13:02:39 +0200 Subject: ALSA: ump: Add helper to change MIDI protocol This is a preliminary patch for MIDI 2.0 USB gadget driver. Export a new helper to allow changing the current MIDI protocol from the outside. Link: https://lore.kernel.org/r/20230621110241.4751-2-tiwai@suse.de Signed-off-by: Takashi Iwai --- sound/core/ump.c | 31 ++++++++++++++++++++++++------- 1 file changed, 24 insertions(+), 7 deletions(-) (limited to 'sound') diff --git a/sound/core/ump.c b/sound/core/ump.c index a64dc2d8a129..4150b9c0b35b 100644 --- a/sound/core/ump.c +++ b/sound/core/ump.c @@ -671,18 +671,35 @@ static void seq_notify_protocol(struct snd_ump_endpoint *ump) #endif /* CONFIG_SND_SEQUENCER */ } +/** + * snd_ump_switch_protocol - switch MIDI protocol + * @ump: UMP endpoint + * @protocol: protocol to switch to + * + * Returns 1 if the protocol is actually switched, 0 if unchanged + */ +int snd_ump_switch_protocol(struct snd_ump_endpoint *ump, unsigned int protocol) +{ + protocol &= ump->info.protocol_caps; + if (protocol == ump->info.protocol) + return 0; + + ump->info.protocol = protocol; + ump_dbg(ump, "New protocol = %x (caps = %x)\n", + protocol, ump->info.protocol_caps); + seq_notify_protocol(ump); + return 1; +} +EXPORT_SYMBOL_GPL(snd_ump_switch_protocol); + /* handle EP stream config message; update the UMP protocol */ static int ump_handle_stream_cfg_msg(struct snd_ump_endpoint *ump, const union snd_ump_stream_msg *buf) { - unsigned int old_protocol = ump->info.protocol; - - ump->info.protocol = + unsigned int protocol = (buf->stream_cfg.protocol << 8) | buf->stream_cfg.jrts; - ump_dbg(ump, "Current protocol = %x (caps = %x)\n", - ump->info.protocol, ump->info.protocol_caps); - if (ump->parsed && ump->info.protocol != old_protocol) - seq_notify_protocol(ump); + + snd_ump_switch_protocol(ump, protocol); return 1; /* finished */ } -- cgit v1.2.3-70-g09d2