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Do pulseaudio 2.1 profile select the internal subwoofer or your 5.1 external speaker ?

My external speaker (i.e not subwoofer but center). It always was so.

https://git.kernel.org/cgit/linux/kernel/git/tiwai/sound.git/commit/sound/pc...

+/* default channel maps for 2.1 speakers; + * since HD-audio supports only stereo, odd number channels are omitted + */ +const struct snd_pcm_chmap_elem snd_pcm_2_1_chmaps[] = { + { .channels = 2, + .map = { SNDRV_CHMAP_FL, SNDRV_CHMAP_FR } }, + { .channels = 4, + .map = { SNDRV_CHMAP_FL, SNDRV_CHMAP_FR, + SNDRV_CHMAP_LFE, SNDRV_CHMAP_LFE } }, + { } +};

The default 2.1 channel map for internal subwoofer does not has 5.1 channel map

But your notebook have three jacks at ext front which support 5.1 In your case,there is no default 2.1 channel map when the current model has three speaker pins

after remove the not exist internal surround speakers,

[ALC882_FIXUP_ACER_ASPIRE_4930G] = { - .type = HDA_FIXUP_PINS, - .v.pins = (const struct hda_pintbl[]) { - { 0x16, 0x99130111 }, /* CLFE speaker */ - { 0x17, 0x99130112 }, /* surround speaker */ - { } - },

you need to use the left channel version of 2.1 channel and 5.1 channel map

+static const struct snd_pcm_chmap_elem acer_pcm_chmaps[] = {

+ { .channels = 2, + .map = { SNDRV_CHMAP_FL, SNDRV_CHMAP_FR } }, + { .channels = 4, + .map = { SNDRV_CHMAP_FL, SNDRV_CHMAP_FR,

+ SNDRV_CHMAP_LFE, SNDRV_CHMAP_NA } }, /* LFE only on left */

+ { .channels = 4, + .map = { SNDRV_CHMAP_FL, SNDRV_CHMAP_FR,

+ SNDRV_CHMAP_RL, SNDRV_CHMAP_RR } },

+ { .channels = 6,

+ .map = { SNDRV_CHMAP_FL, SNDRV_CHMAP_FR,

+ SNDRV_CHMAP_RL, SNDRV_CHMAP_RR,

+ SNDRV_CHMAP_FC, SNDRV_CHMAP_LFE } },

+ { }

+};

http://git.alsa-project.org/?p=alsa-lib.git;a=commitdiff;h=48f1b308cc66152eb... http://git.alsa-project.org/?p=alsa-lib.git;a=commitdiff;h=48f1b308cc66152eb6db66742dd0d08d888cda8d;hp=5c4cd46810cef8850b037fca9e38ffd43b0bff22

conf: Allow 2.1 surround to use different number of channels

This way, cards that support LFE on four channels (e g laptop with internal subwoofer) can do that, and other cards on a six channel setup can use that as well.

which channel map is used by alsa lib when you open surround21 pcm device since your notebook will have both channel maps ?