From: Rong Zhang Date: Tue, 3 Mar 2026 19:48:01 +0000 (+0800) Subject: ALSA: usb-audio: Add QUIRK_FLAG_MIXER_{PLAYBACK,CAPTURE}_LINEAR_VOL X-Git-Tag: v7.1-rc1~166^2~9^2~91 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=3787a6a10e707fca1a61d364a7c256c59823ed59;p=thirdparty%2Fkernel%2Flinux.git ALSA: usb-audio: Add QUIRK_FLAG_MIXER_{PLAYBACK,CAPTURE}_LINEAR_VOL Some quirky devices tune their volume by linearly tuning the voltage level (linear volume). In other words, such devices has a linear TLV mapping of DECLARE_TLV_DB_LINEAR(scale, TLV_DB_GAIN_MUTE, 0). Add quirk flags MIXER_PLAYBACK_LINEAR_VOL and MIXER_CAPTURE_LINEAR_VOL to represent this case respectively for playback and capture mixers. No functional change intended. Signed-off-by: Rong Zhang Signed-off-by: Takashi Iwai Link: https://patch.msgid.link/20260303194805.266158-7-i@rong.moe --- diff --git a/Documentation/sound/alsa-configuration.rst b/Documentation/sound/alsa-configuration.rst index 55b845d382368..f75f087639415 100644 --- a/Documentation/sound/alsa-configuration.rst +++ b/Documentation/sound/alsa-configuration.rst @@ -2376,6 +2376,13 @@ quirk_flags Skip the probe-time interface setup (usb_set_interface, init_pitch, init_sample_rate); redundant with snd_usb_endpoint_prepare() at stream-open time + * bit 27: ``mixer_playback_linear_vol`` + Set linear volume mapping for devices where the playback volume + control value is mapped to voltage (instead of dB) level linearly. + In short: ``x(raw) = (raw - raw_min) / (raw_max - raw_min)``; + ``V(x) = k * x``; ``dB(x) = 20 * log10(x)``. Overrides bit 24 + * bit 28: ``mixer_capture_linear_vol`` + Similar to bit 27 but for capture streams. Overrides bit 25 This module supports multiple devices, autoprobe and hotplugging. diff --git a/sound/usb/mixer_quirks.c b/sound/usb/mixer_quirks.c index 11e205da7964d..539044c0c6440 100644 --- a/sound/usb/mixer_quirks.c +++ b/sound/usb/mixer_quirks.c @@ -4634,6 +4634,25 @@ triggered: usb_audio_dbg(chip, "something wrong in kctl name %s\n", id->name); } +static void snd_usb_mixer_fu_quirk_linear_scale(struct usb_mixer_interface *mixer, + struct usb_mixer_elem_info *cval, + struct snd_kcontrol *kctl) +{ + static const DECLARE_TLV_DB_LINEAR(scale, TLV_DB_GAIN_MUTE, 0); + + if (cval->min_mute) { + /* + * We are clearing SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK, + * resulting in min_mute being a no-op. + */ + usb_audio_warn(mixer->chip, "LINEAR_VOL overrides MIN_MUTE\n"); + } + + kctl->tlv.p = scale; + kctl->vd[0].access |= SNDRV_CTL_ELEM_ACCESS_TLV_READ; + kctl->vd[0].access &= ~SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK; +} + void snd_usb_mixer_fu_apply_quirk(struct usb_mixer_interface *mixer, struct usb_mixer_elem_info *cval, int unitid, struct snd_kcontrol *kctl) @@ -4660,6 +4679,21 @@ void snd_usb_mixer_fu_apply_quirk(struct usb_mixer_interface *mixer, "applying capture min mute quirk\n"); cval->min_mute = 1; } + + if (mixer->chip->quirk_flags & QUIRK_FLAG_MIXER_PLAYBACK_LINEAR_VOL) + if (cval->control == UAC_FU_VOLUME && strstr(kctl->id.name, "Playback")) { + usb_audio_info(mixer->chip, + "applying playback linear volume quirk\n"); + snd_usb_mixer_fu_quirk_linear_scale(mixer, cval, kctl); + } + + if (mixer->chip->quirk_flags & QUIRK_FLAG_MIXER_CAPTURE_LINEAR_VOL) + if (cval->control == UAC_FU_VOLUME && strstr(kctl->id.name, "Capture")) { + usb_audio_info(mixer->chip, + "applying capture linear volume quirk\n"); + snd_usb_mixer_fu_quirk_linear_scale(mixer, cval, kctl); + } + /* ALSA-ify some Plantronics headset control names */ if (USB_ID_VENDOR(mixer->chip->usb_id) == 0x047f && (cval->control == UAC_FU_MUTE || cval->control == UAC_FU_VOLUME)) diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c index 00d1a7c2260e7..7a5cec9cc4bd9 100644 --- a/sound/usb/quirks.c +++ b/sound/usb/quirks.c @@ -2543,6 +2543,8 @@ static const char *const snd_usb_audio_quirk_flag_names[] = { QUIRK_STRING_ENTRY(MIXER_PLAYBACK_MIN_MUTE), QUIRK_STRING_ENTRY(MIXER_CAPTURE_MIN_MUTE), QUIRK_STRING_ENTRY(SKIP_IFACE_SETUP), + QUIRK_STRING_ENTRY(MIXER_PLAYBACK_LINEAR_VOL), + QUIRK_STRING_ENTRY(MIXER_CAPTURE_LINEAR_VOL), NULL }; diff --git a/sound/usb/usbaudio.h b/sound/usb/usbaudio.h index 085530cf62d92..58fd07f8c3c97 100644 --- a/sound/usb/usbaudio.h +++ b/sound/usb/usbaudio.h @@ -228,6 +228,14 @@ extern bool snd_usb_skip_validation; * Skip the probe-time interface setup (usb_set_interface, * init_pitch, init_sample_rate); redundant with * snd_usb_endpoint_prepare() at stream-open time + * QUIRK_FLAG_MIXER_PLAYBACK_LINEAR_VOL + * Set linear volume mapping for devices where the playback volume control + * value is mapped to voltage (instead of dB) level linearly. In short: + * x(raw) = (raw - raw_min) / (raw_max - raw_min); V(x) = k * x; + * dB(x) = 20 * log10(x). Overrides QUIRK_FLAG_MIXER_PLAYBACK_MIN_MUTE + * QUIRK_FLAG_MIXER_CAPTURE_LINEAR_VOL + * Similar to QUIRK_FLAG_MIXER_PLAYBACK_LINEAR_VOL, but for capture streams. + * Overrides QUIRK_FLAG_MIXER_CAPTURE_MIN_MUTE */ enum { @@ -258,6 +266,8 @@ enum { QUIRK_TYPE_MIXER_PLAYBACK_MIN_MUTE = 24, QUIRK_TYPE_MIXER_CAPTURE_MIN_MUTE = 25, QUIRK_TYPE_SKIP_IFACE_SETUP = 26, + QUIRK_TYPE_MIXER_PLAYBACK_LINEAR_VOL = 27, + QUIRK_TYPE_MIXER_CAPTURE_LINEAR_VOL = 28, /* Please also edit snd_usb_audio_quirk_flag_names */ }; @@ -290,5 +300,7 @@ enum { #define QUIRK_FLAG_MIXER_PLAYBACK_MIN_MUTE QUIRK_FLAG(MIXER_PLAYBACK_MIN_MUTE) #define QUIRK_FLAG_MIXER_CAPTURE_MIN_MUTE QUIRK_FLAG(MIXER_CAPTURE_MIN_MUTE) #define QUIRK_FLAG_SKIP_IFACE_SETUP QUIRK_FLAG(SKIP_IFACE_SETUP) +#define QUIRK_FLAG_MIXER_PLAYBACK_LINEAR_VOL QUIRK_FLAG(MIXER_PLAYBACK_LINEAR_VOL) +#define QUIRK_FLAG_MIXER_CAPTURE_LINEAR_VOL QUIRK_FLAG(MIXER_CAPTURE_LINEAR_VOL) #endif /* __USBAUDIO_H */