tests/kms_chamelium: add dp-audio test

This new test ensures DisplayPort audio works by using the Chamelium.

It enables the DisplayPort output and sends an audio signal containing a set of
frequencies we choose to all HDMI/DisplayPort audio devices. It starts
recording audio on the Chamelium device and uses the stream server to retrieve
captured audio pages. It then checks that the capture audio signal contains the
frequencies we sent, and only those, by computing a FFT.

A new library has been added to libigt to communicate with the stream server.
It implements a simple custom TCP protocol.

In case the test fails, a WAV file with the captured data is saved on disk.

Right now the test has a few limitations:

- Only the first channel is checked
- IGT only generates audio with a single sampling rate (48 KHz)
- Audio data is not captured in real-time

These limitations will be lifted in future patches.

PulseAudio must not run during the tests since ALSA is used directly. To ensure
this, edit /etc/pulse/client.conf and add `autospawn=no`. Then run
`pulseaudio --kill`.

This commit deletes the existing audio tests. They weren't run and required an
exotic configuration (HDMI audio splitter, dummy HDMI sink and a line-in port
on the DUT).

This patch also changes lib/igt_audio to use uint16_t instead of short. The
rationale is:

- The standard says a short is at least 16 bit wide, but a short can be
  larger (in practice it won't happen, but better use types correctly)
- It makes it clearer that the audio format is S16_LE, since "16" is
  in the type name.

This patch depends on the following Chameleon bugs:

- https://crbug.com/948060
- https://crbug.com/950857

Signed-off-by: Simon Ser <simon.ser@intel.com>
Reviewed-by: Martin Peres <martin.peres@linux.intel.com>

1 files changed, 0 insertions, 45 deletions

diff --git a/docs/audio.txt b/docs/audio.txt
deleted file mode 100644
index 158ad5d1..00000000
--- a/docs/audio.txt
+++ /dev/null
@@ -1,45 +0,0 @@
-Audio Support in IGT
-====================
-
-This document provides information and instructions about audio support in IGT.
-
-Introduction
-------------
-
-The audio test is aimed at testing the audio features of display connectors,
-such as HDMI.
-
-Test setup
-----------
-
-The setup required for the audio test consists of using an HDMI-VGA adapter with
-an audio-out 3.5 mm jack to extract the audio from the HDMI interface.
-The audio-out jack is connected back to the device-under-test's line-in.
-
-Depending on the behavior of the adapter, it may be necessary to connect a
-ghost VGA dongle to it (in order to emulate a connected display) to enable the
-audio output. There are guides available detailing how to build these.
-
-When executed, the test will automatically send the test audio signal to all
-ALSA audio HDMI outputs and record from the standard ALSA capture device.
-
-Configuration
--------------
-
-In order to deploy the test, ALSA controls have to be configured to set the
-ALSA capture source to line-in. On Intel x86 systems, this can be achieved
-with the following calls to the amixer utility:
-# amixer sset Line 31 on
-# amixer sset "Input Source" Line
-
-It is then useful to store the ALSA state permanently with the alsactl utility:
-# alsactl store
-
-These settings can be restored with the alsactl utility:
-# alsactl restore
-
-It is desirable to ensure that the alsa-restore and alsa-state systemd services
-are enabled to do this job automatically, especially in the case of an
-automated testing system:
-# systemctl enable alsa-restore
-# systemctl enable alsa-state