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>

2 files changed, 28 insertions, 51 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
diff --git a/docs/chamelium.txt b/docs/chamelium.txt
index 0cabcdc6..5cc85d6e 100644
--- a/docs/chamelium.txt
+++ b/docs/chamelium.txt
@@ -139,6 +139,23 @@ $ make remote-install CHAMELEON_HOST=192.168.72.1
 
 The process requires the Chamelium to be connected to the Internet to succeed.
 
+Audio Capture
+-------------
+
+The Chamelium supports audio capture. IGT tests take advantage of the
+Chamelium streaming server to download audio samples from the Chamelium.
+
+IGT needs direct access to audio devices through ALSA, so PulseAudio needs to
+be stopped (otherwise audio tests will automatically get skipped). To make sure
+PulseAudio isn't running:
+
+- Edit /etc/pulse/client.conf and add autospawn=no
+- Run `pulseaudio --kill` (if it succeeds, it means PulseAudio was running)
+- Make sure a DE that automatically spawns PulseAudio isn't running
+
+In case a test fails, the raw captured audio files will be dumped in a WAV
+file.
+
 Contributing Changes to the Daemon
 ----------------------------------
 
@@ -146,10 +163,11 @@ Contributions to the Chamelium daemon, just like any contribution to ChromiumOS,
 are submitted and reviewed at: https://chromium-review.googlesource.com/
 
 The ChromiumOS project provides an extensive developer guide:
-https://www.chromium.org/chromium-os/developer-guide that assumes running within
-the ChromiumOS build system. Since this is likely not the case for contributing
-to the Chamelium daemon, only the part about uploading changes is relevant:
-https://www.chromium.org/chromium-os/developer-guide#TOC-Upload-your-changes-and-get-a-code-review
+https://chromium.googlesource.com/chromiumos/docs/+/master/developer_guide.md
+It assumes running within the ChromiumOS build system. Since this is likely not
+the case for contributing to the Chamelium daemon, only the part about
+uploading changes is relevant:
+https://chromium.googlesource.com/chromiumos/docs/+/master/developer_guide.md#Upload-your-changes-and-get-a-code-review
 
 Most of the process is about using the Gerrit web interface for submitting and
 having the change reviewed and not forgetting the Change-Id, TEST= and BUG=
@@ -162,7 +180,7 @@ Support for the Chamelium platform in IGT is found in the following places:
 * lib/igt_chamelium.c: library with Chamelium-related helpers
 * tests/kms_chamelium.c: sub-tests using the Chamelium
 
-As of late August 2017, the following features are tested by IGT:
+As of early April 2019, the following features are tested by IGT:
 * Pixel-by-pixel frame integrity tests for DP and HDMI
 * Error-trend-based frame integrity tests for VGA
 * CRC-based frame integrity tests for DP and HDMI
@@ -173,6 +191,7 @@ As of late August 2017, the following features are tested by IGT:
   each interface or combined
 * EDID display identifier integrity check for all interfaces
 * EDID display identifier change during suspend for all interfaces
+* Audio Fourier-based tests for DP at 48KHz
 
 Future Developments
 -------------------
@@ -180,7 +199,10 @@ Future Developments
 With the current generation of the hardware platform, support for testing a
 number of additional display features could be included as future developments,
 including:
-* Audio capture from HDMI and DP
+* Audio capture from HDMI
+* Check all channels are independent from each other
+* Playback using more than 2 channels, different sampling rates and different
+  sample sizes
 * High-bandwidth Digital Content Protection (HDCP) streaming to the display
 * Remote control forwarding (CEC) sent from the display
 * YUV colorspace for HDMI, instead of RGB