On Sat, 13 May 2023 22:20:35 +0200, Ivan Orlov wrote:
Add documentation for the new Virtual ALSA driver. It covers all possible usage cases: errors and delay injections, random and pattern-based data generation, playback and ioctl redefinition functionalities testing.
We have a lot of different virtual media drivers, which can be used for testing of the userspace applications and media subsystem middle layer. However, all of them are aimed at testing the video functionality and simulating the video devices. For audio devices we have only snd-dummy module, which is good in simulating the correct behavior of an ALSA device. I decided to write a tool, which would help to test the userspace ALSA programs (and the PCM middle layer as well) under unusual circumstances to figure out how they would behave. So I came up with this Virtual ALSA Driver.
This new Virtual ALSA Driver has several features which can be useful during the userspace ALSA applications testing/fuzzing, or testing/fuzzing of the PCM middle layer. Not all of them can be implemented using the existing virtual drivers (like dummy or loopback). Here is what can this driver do:
- Simulate both capture and playback processes
- Check the playback stream for containing the looped pattern
- Generate random or pattern-based capture data
- Inject delays into the playback and capturing processes
- Inject errors during the PCM callbacks
Also, this driver can check the playback stream for containing the predefined pattern, which is used in the corresponding selftest to check the PCM middle layer data transferring functionality. Additionally, this driver redefines the default RESET ioctl, and the selftest covers this PCM API functionality as well.
Signed-off-by: Ivan Orlov ivan.orlov0322@gmail.com
Documentation/admin-guide/index.rst | 1 + Documentation/admin-guide/valsa.rst | 114 ++++++++++++++++++++++++++++
We have already subdirectories for the sound stuff (Documentation/sound/*), and this should go to there, I suppose (unless there is somewhere dedicated for each selftest scenario).
thanks,
Takashi