From a050fabb16a5529a83e9d461b99056ae48761f5b Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Piotr=20Gli=C5=BAniewicz?= Date: Fri, 16 Oct 2026 09:31:31 +0200 Subject: [PATCH] ALSA: 6fire: add a playback channel map MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The driver registers no "Playback Channel Map" control, so a program that needs the speaker position of each playback channel has to assume an order; speaker-test, for example, assumes FL FR RL RR FC LFE for 6 channels. Channel n of the PCM goes to Line Out n, and the manual of the card assigns Line Out 1 to 6 to front left and right, centre and subwoofer, and rear left and right. Add a playback channel map in the order of the manual, FL FR FC LFE RL RR. A stream with 2 to 5 channels gets the first positions of the list. A 1-channel stream gets MONO, as in every 1-channel entry of a channel map in sound/; the card plays it on Line Out 1 only. The map has an entry for every channel count from 1 to 6, because reading the control fails with -EINVAL for a count without an entry. Tested on a DMX 6Fire USB with kernel 7.2.10: during playback with 1, 3, 5 and 6 channels the control reads MONO, FL FR FC, FL FR FC LFE RL and FL FR FC LFE RL RR, and the "Front Center" test of speaker-test -c 6 played on Line Out 3. Assisted-by: LLM Signed-off-by: Piotr Gliźniewicz Signed-off-by: Takashi Iwai Link: https://patch.msgid.link/20261016073132.109288-3-p.glizniewicz@gmail.com --- sound/usb/6fire/pcm.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) diff --git a/sound/usb/6fire/pcm.c b/sound/usb/6fire/pcm.c index 0285d79ace0f..d99395229eb2 100644 --- a/sound/usb/6fire/pcm.c +++ b/sound/usb/6fire/pcm.c @@ -612,6 +612,28 @@ static void usb6fire_pcm_free(struct pcm_runtime *rt) kfree(rt); } +/* + * playback channel map: channel n goes to analog output n, which the + * manual of the card assigns to FL FR FC LFE RL RR for n = 1..6; a + * 1-channel stream is MONO, as in snd_pcm_std_chmaps, and plays on + * analog output 1 only + */ +static const struct snd_pcm_chmap_elem usb6fire_pcm_chmaps[] = { + { .channels = 1, .map = { SNDRV_CHMAP_MONO } }, + { .channels = 2, .map = { SNDRV_CHMAP_FL, SNDRV_CHMAP_FR } }, + { .channels = 3, .map = { SNDRV_CHMAP_FL, SNDRV_CHMAP_FR, + SNDRV_CHMAP_FC } }, + { .channels = 4, .map = { SNDRV_CHMAP_FL, SNDRV_CHMAP_FR, + SNDRV_CHMAP_FC, SNDRV_CHMAP_LFE } }, + { .channels = 5, .map = { SNDRV_CHMAP_FL, SNDRV_CHMAP_FR, + SNDRV_CHMAP_FC, SNDRV_CHMAP_LFE, + SNDRV_CHMAP_RL } }, + { .channels = 6, .map = { SNDRV_CHMAP_FL, SNDRV_CHMAP_FR, + SNDRV_CHMAP_FC, SNDRV_CHMAP_LFE, + SNDRV_CHMAP_RL, SNDRV_CHMAP_RR } }, + { } +}; + int usb6fire_pcm_init(struct sfire_chip *chip) { int i; @@ -665,6 +687,14 @@ int usb6fire_pcm_init(struct sfire_chip *chip) rt->instance = pcm; chip->pcm = rt; + + /* on error, rt is freed with the card */ + ret = snd_pcm_add_chmap_ctls(pcm, SNDRV_PCM_STREAM_PLAYBACK, + usb6fire_pcm_chmaps, OUT_N_CHANNELS, 0, NULL); + if (ret < 0) { + dev_err(&chip->dev->dev, "cannot add channel map.\n"); + return ret; + } return 0; error: