Using HDMI With ATI Radeon HD Linux Drivers

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One of the special abilities of ATI's R600 GPU family is the integrated
5.1 surround sound audio support through HDMI. Many Radeon HD 2000 and
HD 3800 series graphics cards also ship with a DVI to HDMI dongle, so
that one can experience the full video playback capabilities of these
discrete graphics cards. But what level of HDMI support can Linux users
expect when using these latest ATI graphics cards? We have done some
testing internally and have the initial ATI Linux HDMI video and audio
results to report in this article.
The graphics card used for this Linux HDMI (High Definition Media
Interface) testing was the ASUS Radeon HD 2600PRO 256MB, which was
connected via a DVI-to-HDMI dongle to a Sharp Aquos LC37D43U 37" LCD
HDTV. For the video portion of the HDMI, we had tested both the fglrx
and RadeonHD drivers and ALSA for audio.
Using the ATI Linux "fglrx" driver, the system running Ubuntu 7.10 had
booted without any issues and was running at 1920 x 1080 through no
end-user intervention or manually specifying any display modes.
Entering the AMD Catalyst Control Center Linux Edition, there were no
problems with managing the Sharp HDMI display and everything had worked
out smoothly.
At 1920 x 1080, the Radeon HD 2600PRO had no problems running Compiz
Fusion at this resolution. Enemy Territory: Quake Wars was also running
at this resolution and high-quality settings, with an average
frame-rate of ~26 FPS. Everything on the display front had worked out,
though we didn't expect any problems as this was just running through
an included DVI-to-HDMI dongle.
Unfortunately, the HDMI audio at this time wasn't nice. Ubuntu 7.10
ships with ALSA 1.0.14, so we had manually compiled ALSA 1.0.15. A
patch for R600, RS600, RS690, RS780 HDMI audio support was originally
released by AMD earlier this year, and is present in this latest
version of ALSA (Advanced Linux Sound Architecture). However, ALSA was
unable to properly detect and utilize this ATI R600 HDMI audio adapter
through the hda-intel driver. For the record, there are bugs present in
ALSA 1.0.15 that affect other adapters using HDMI audio as well. For
right now, using the HDMI audio with the latest ATI Radeon HD graphics
cards isn't a trouble-free experience, but hopefully once ALSA 1.0.16
is out the door these problems will be eliminated.
After the success using the proprietary ATI driver, we had turned to
the latest git code for xf86-video-radeonhd. Using this open-source
driver, the detected EDID information from the Sharp LC37D43U LCD HDTV
had the system running at 1280 x 720. We had then manually added a 1920
x 1080 mode in the xorg.conf, but still the RadeonHD driver had turned
back to this lower resolution. Aside from the resolution disparity, the
RadeonHD driver worked fine as would be expected for this HDMI adapter.
               
               
               

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