From 78811dd56def1479777c9823f3c2139739ef5bf5 Mon Sep 17 00:00:00 2001 From: Cryolitia PukNgae Date: Fri, 29 Aug 2025 16:46:06 +0800 Subject: [PATCH] ALSA: docs: Add documents for recently changes in snd-usb-audio Changed: - ignore_ctl_error - lowlatency - skip_validation - quirk_flags[19:24] [ corrected a typo -- tiwai ] Signed-off-by: Cryolitia PukNgae Link: https://patch.msgid.link/20250829-sound-doc-v1-1-e0110452b03d@uniontech.com Signed-off-by: Takashi Iwai --- Documentation/sound/alsa-configuration.rst | 29 +++++++++++++++++++--- 1 file changed, 25 insertions(+), 4 deletions(-) diff --git a/Documentation/sound/alsa-configuration.rst b/Documentation/sound/alsa-configuration.rst index a45174d165ebd..062b86522e4d9 100644 --- a/Documentation/sound/alsa-configuration.rst +++ b/Documentation/sound/alsa-configuration.rst @@ -2253,8 +2253,15 @@ device_setup Default: 0x0000 ignore_ctl_error Ignore any USB-controller regarding mixer interface (default: no) + ``ignore_ctl_error=1`` may help when you get an error at accessing + the mixer element such as URB error -22. This happens on some + buggy USB device or the controller. This workaround corresponds to + the ``quirk_flags`` bit 14, too. autoclock Enable auto-clock selection for UAC2 devices (default: yes) +lowlatency + Enable low latency playback mode (default: yes). + Could disable it to switch back to the old mode if face a regression. quirk_alias Quirk alias list, pass strings like ``0123abcd:5678beef``, which applies the existing quirk for the device 5678:beef to a new @@ -2284,6 +2291,11 @@ delayed_register The driver prints a message like "Found post-registration device assignment: 1234abcd:04" for such a device, so that user can notice the need. +skip_validation + Skip unit descriptor validation (default: no). + The option is used to ignores the validation errors with the hexdump + of the unit descriptor instead of a driver probe error, so that we + can check its details. quirk_flags Contains the bit flags for various device specific workarounds. Applied to the corresponding card index. @@ -2307,6 +2319,16 @@ quirk_flags * bit 16: Set up the interface at first like UAC1 * bit 17: Apply the generic implicit feedback sync mode * bit 18: Don't apply implicit feedback sync mode + * bit 19: Don't closed interface during setting sample rate + * bit 20: Force an interface reset whenever stopping & restarting + a stream + * bit 21: Do not set PCM rate (frequency) when only one rate is + available for the given endpoint. + * bit 22: Set the fixed resolution 16 for Mic Capture Volume + * bit 23: Set the fixed resolution 384 for Mic Capture Volume + * bit 24: Set minimum volume control value as mute for devices + where the lowest playback value represents muted state instead + of minimum audible volume This module supports multiple devices, autoprobe and hotplugging. @@ -2314,10 +2336,9 @@ NB: ``nrpacks`` parameter can be modified dynamically via sysfs. Don't put the value over 20. Changing via sysfs has no sanity check. -NB: ``ignore_ctl_error=1`` may help when you get an error at accessing -the mixer element such as URB error -22. This happens on some -buggy USB device or the controller. This workaround corresponds to -the ``quirk_flags`` bit 14, too. +NB: ``ignore_ctl_error=1`` just provides a quick way to work around the +issues. If you have a buggy device that requires these quirks, please +report it to the upstream. NB: ``quirk_alias`` option is provided only for testing / development. If you want to have a proper support, contact to upstream for -- 2.51.0