Getting the audio over HDMI to work for the HP N54L microserver running Debian Wheezy and a Sapphire Radeon HD 6450

Conclusion: Sound over HDMI works with the Sapphire Radeon HD 6450 card in my HP N54L microserver. It requires a recent kernel and firmware from Wheezy 7.7 backports and the X.org server. There is no sound without X.org, even if audio has been enabled for the radeon kernel module.

Last year I couldn't get audio over HDMI to work after I installed a Sapphire Radeon HD 6450 1 GB (11190-02-20g) card into my N54L microserver. The cable that connects the HDMI interfaces between the card and the TV monitor supports HDMI 1.3, so audio should have been possible even then. However, I didn't get any audio output by XBMC playing video or music files. Nothing happened with stock Wheezy 7.1 and X.org/XBMC installed. So I removed the latter two and used the server as stock server without X/desktop and delayed my plans for an HTPC.

Now I tried again after I found some new hints, that made me curious for a second try :) Imagine my joy, when (finally) speaker-test produced noise on the TV! So here is my configuration and a step-by-step guide to

• enable Sound over HDMI for the Radeon HD 6450
• install a graphical environment
• install XBMC
• automatically start XBMC on boot

The latter two will be covered by a second post. Also note, that there is lot of information out there to achive the above tasks. So this is only about my configuration. Some packages below are marked as optional. A few are necessary only for the N54L microserver (firmware) and for a few I'm not sure they are necessary at all.

Step 1 - Prepare the system

At this point I don't have any desktop nor any other graphical environment (X.org) installed. First I purged pulseaudio and related packages completely and only use ALSA:

# apt-get autoremove --purge pulseaudio pulseaudio-utils pulseaudio-module-x11 gstreamer0.10-pulseaudio
# apt-get install alsa-base alsa-utils alsa-oss

Next I installed a recent linux kernel and recent firmware from Wheezy backports:

# apt-get install -t wheezy-backports linux-image-amd64 firmware-linux-free firmware-linux firmware-linux-nonfree firmware-atheros firmware-bnx2 firmware-bnx2x

This put linux-image-3.16-0.bpo.3-amd64 and recent firmware onto my system. I've chosen to upgrade linux-image-amd64 instead to pick a special (recent) linux kernel package from Wheezy backports to keep up-to-date with recent kernels from there.

Then I enabled the audio output of the kernel radeon module. Essentially there are at least three ways to do this. I use the one to modify /etc/modules.d/radeon.conf and set the audio parameter there. The hw_i2c parameter is disabled. I read, that it might cause trouble with the audio output here although I never personally experienced it:

options radeon audio=1 hw_i2c=0

JFTR: This is how I boot the N54L by default:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi=force pcie_aspm=force nmi_watchdog=0"

After rebooting I see this for the Radeon card in question:

# lsmod | egrep snd\|radeon\|drm | awk '{print $1}' | sort
[..]
drm
drm_kms_helper
i2c_algo_bit
i2c_core
radeon
snd
snd_hda_codec
snd_hda_codec_hdmi
snd_hda_controller
snd_hda_intel
snd_hwdep
snd_pcm
snd_seq
snd_seq_device
snd_timer
soundcore
ttm
[..]
# lspci -k
[..]
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Caicos [Radeon HD 6450/7450/8450 / R5 230 OEM]
        Subsystem: PC Partner Limited / Sapphire Technology Device e204
        Kernel driver in use: radeon
01:00.1 Audio device: Advanced Micro Devices, Inc. [AMD/ATI] Caicos HDMI Audio [Radeon HD 6400 Series]
        Subsystem: PC Partner Limited / Sapphire Technology Radeon HD 6450 1GB DDR3
        Kernel driver in use: snd_hda_intel
[..]
# cat  /sys/module/radeon/parameters/audio 
1
# cat  /sys/module/radeon/parameters/hw_i2c 
0
# aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: HDMI [HDA ATI HDMI], device 3: HDMI 0 [HDMI 0]
  Subdevices: 0/1
  Subdevice #0: subdevice #0
# aplay -L
null
    Discard all samples (playback) or generate zero samples (capture)
pulse
    PulseAudio Sound Server
hdmi:CARD=HDMI,DEV=0
    HDA ATI HDMI, HDMI 0
    HDMI Audio Output

At this point, without having the X.org server installed, I still have no audio output to the connected monitor. Running alsamixer I only see the S/PDIF bar for the HDA ATI HDMI device, showing a value of 00. I can mute and un-mute this device but not change the value. No need to worry, sound comes with step two.

Step 2 - Install a graphical environment (X.org server)

Next is to install a graphical environment, basically the X.org server. This is done in Debian by the desktop task. Unfortunately tasksel makes use of APT::Install-Recommends="true" and would install a desktop environment and some more recommended packages. At the moment I don't want this, only X. So basically I installed only the task-desktop package with dependencies:

# apt-get install task-desktop xfonts-cyrillic

Next is to install a display manager. I've chosen lightdm:

# apt-get install lightdm accountsservice

Done. Now (re-)start the X server. Simply ...

# service lightdm restart

... should do. And now there is sound, probably due to the X.org Radeon driver. The following command created noise on the two monitor speakers :)

# speaker-test -c2 -D hdmi:0 -t pink

Finally there is sound over HDMI!

Step 3 - Install XBMC

To be continued ...