Common ALSA module parameters look a little bit confusing because of the
description lacking, and it took me a while to understand the purpose of
their existence. To figure it out I asked the question about them to the
"alsa-devel" mailing list, and Takashi Iwai answered me with the text I
appended to the ALSA documentation in this patch.
These common module parameters aren't used a lot nowadays, but as I
understand they are important for providing compatibility with some
existing user-space apps. So in my opinion it is a good idea to document
why we need them.
Signed-off-by: Ivan Orlov <ivan.orlov0322@xxxxxxxxx>
---
Documentation/sound/alsa-configuration.rst | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/Documentation/sound/alsa-configuration.rst b/Documentation/sound/alsa-configuration.rst
index af71c68f1e4e..829c672d9fe6 100644
--- a/Documentation/sound/alsa-configuration.rst
+++ b/Documentation/sound/alsa-configuration.rst
@@ -133,6 +133,19 @@ enable
enable card;
Default: enabled, for PCI and ISA PnP cards
+These options are used for either specifying the order of instances or
+controlling enabling and disabling of each one of the devices if there
+are multiple devices bound with the same driver. For example, there are
+many machines which have two HD-audio controllers (one for HDMI/DP
+audio and another for onboard analog). In most cases, the second one is
+in primary usage, and people would like to assign it as the first
+appearing card. They can do it by specifying "index=1,0" module
+parameter, which will swap the assignment slots.
+
+Today, with the sound backend like PulseAudio and PipeWire which
+supports dynamic configuration, it's of little use, but that was a
+help for static configuration in the past.
+
Module snd-adlib
----------------
--
2.34.1
