Each configuration file represents an audio stream topology i.e.: connections of AudioDSP pipelines and processing modules that provide rich user experience with the Intel AVS stack. The avs-driver is part of the Linux kernel sound subsystem, sound/soc/intel/avs.
Related to alsa-topology-conf yet instead of UseCaseManagement (UCM) files, topologies found here are XML document files.
As the audio stack supports audio transfer over multiple interfaces, repository consists of directories representing one interface each.
Kernel sound drivers are not capable of consuming topologies in their XML format. In order to obtain kernel-friendly format, topology needs to be converted to UCM format first using avstplg tool and then finally to binary using alsatplg, which is available by default on any Linux distribution.
Flow of conversion, from XML to bin:
XML -> avstplg -> UCM
UCM -> alsatplg -> bin
Result binaries are to be placed under /lib/firmware/intel/avs so they can be loaded by the
kernel.
Note: the avs-driver loads only topologies for devices that have successfully enumerated during
system boot and are listed in supported configurations list found in:
board_selection.c
file.
Digital Microphone support. Repository contains universal, multi-format topology that should work on all Intel platforms equipped with AudioDSP, starting from Skylake onward.
HDAudio codec expose anywhere between one to three uni or bidirectional endpoints: Analog/Digital/Alt Analog. The actual number of supported endpoints and their description is obtained during codec enumeration on the HDAudio bus.
Repository contains simple, generic reference for single-endpoint variant which should work for any HDaudio configuration.
Follows the similar scheme as the HDAudio. The directory contains topology files
supporting Intel-devices only, that is HDAudio codecs that expose 0x8086 as their Vendor ID.
Another specific detail is that no capture streams are part of those topologies - all the HDMI
endpoints are unidirectional.
In general, given the PlatformControllerHub (PCH) generation, a HDMI device falls into: three, five or nine -endpoint category. References for all of them are available.
Least generic out of all available. Often a specific configuration is used per codec device. See sound/soc/intel/avs/boards to check whether given configuration is supported by the kernel driver.
While building a topology file requires some AudioDSP knowledge, especially in the driver <-> firmware interaction area, all contributions are welcome. Project follows submission guidelines similar to those of high-profile projects, such as the Linux kernel.
Commit message title line length is limited to 72 characters.
Scoping shall be used to indicate the context of introduced changes, through adding subdirectory tag ('tag: ') at the beginning of commit's title. Leave the scope out only when submitting repo-wide changes.
The scopes for subdirectories go as follows:
dmic/ dmic
hda/ hda
hdmi/ hdmi
i2s/ i2s
Regardless of type of change you want to submit, it must be described. Please follow Describe your changes guide for the best practises of doing so. The guide is quite lengthy, the essence is captured below:
- State the motivation behind the change
- Be transparent, do not hide things
- Describe user impact if any
- Use imperative mood
- The lower level the problem is, the more detailed the description should be.
- Ensure any links or references appended are actually working
- Keep the line width with 72 characters margin
Optionally, at the bottom of commit message tags (kind of keywords) can be appended. These tags serve informational purposes, further enhancing code documentation and enabling fixes propagation through automated tasks. Below are guides for a range of such tags:
When to use Acked-by:, Cc:, and Co-developed-by:
Using Reported-by:, Tested-by:, Reviewed-by:, Suggested-by: and Fixes:
The final paragraphs of Describe your changes help
setup git config so appending correctly formatted Fixes: tag becomes trivial.