Description:
I use dual-head motheboard MSI 785GM-E51 with AMD southbridge 785GM.
Monitor is connected to the VGA output and the LED TV is connected to the HDMI output.
X-desktop is openbox-based without display manager or sesion manager.
There is no xorg.conf file.

If the system boot with TV connected and on, the auto resolution is 640x480 with the same image on the monitor and TV. In this case HDMI-sound is normal.
Then I turn HDMI output off and on:

xrandr --output HDMI-0 --off
xrandr --output HDMI-0 --mode 1920x1080 --below VGA-0

After this HDMI-sound is roughly twice slower than it should.
If the TV was physically off during system boot and then was on and enabled by xrandr, the result is the same - HDMI-sound is slow.

Additional info:

* package version(s)
The last Arch kernel with no problem is 3.1.9-2-ARCH (I downgraded the kernel only). The 3.10.2 and 3.10.3 kernels have too many HDMI problems, 3.10.5-1-ARCH is the first kernel where THIS problem is visible.

Steps to reproduce:
- Have the motheboard with @normal@ sound, with AMD southbridge 785GM and without discret videocard. Have the HDMI device with HDMI-sound support.
- Connect the monitor to the VGA output and disconnect the HDMI output.
- Boot the system with radeon.audio=1 kernel paramether.
- Connect the HDMI device and turn it on.
- Turn the HDMI output on (f.i. xrandr --output HDMI-0 --mode 1920x1080 --below VGA-0).
- Play a sound to the alsa device HDMI (for the MSI 785GM-E51 motheboard - hw:1.3).

I tryed the mplayer (with -ao alsa:device=hw=1.3 -softvol) and audacious (GUI configurated to hw:1.3), results are the same.

* X and dmesg logs are the same for good and bad kernels, except the kernel and radeon module versions (radeon 2.11.0 and 2.33.0 respectively):


[ak@s2 log]$ grep '(EE)\|radeon' Xorg.0.log
[ 31.725] Current Operating System: Linux s2 3.10.6-2-ARCH #1 SMP PREEMPT Tue Aug 13 10:20:52 CEST 2013 i686
[ 31.725] Kernel command line: root=/dev/sda12 loglevel=3 ro resume=/dev/sda3 radeon.audio=1 vga=867
(WW) warning, (EE) error, (NI) not implemented, (??) unknown.
[ 32.081] (II) LoadModule: "radeon"
[ 32.082] (II) Loading /usr/lib/xorg/modules/drivers/radeon_drv.so
[ 32.103] (II) Module radeon: vendor="X.Org Foundation"
[ 32.117] (EE) Failed to load module "modesetting" (module does not exist, 0)
[ 32.118] (EE) Failed to load module "fbdev" (module does not exist, 0)

[ak@s2 log]$ dmesg | grep radeon
[ 0.000000] Kernel command line: root=/dev/sda12 loglevel=3 ro resume=/dev/sda3 radeon.audio=1 vga=867
[ 8.537038] [drm] radeon kernel modesetting enabled.
[ 8.547654] fb: conflicting fb hw usage radeondrmfb vs VESA VGA - removing generic driver
[ 8.549340] radeon 0000:01:05.0: VRAM: 128M 0x00000000C0000000 - 0x00000000C7FFFFFF (128M used)
[ 8.549342] radeon 0000:01:05.0: GTT: 512M 0x00000000A0000000 - 0x00000000BFFFFFFF
[ 8.553488] [drm] radeon: 128M of VRAM memory ready
[ 8.553490] [drm] radeon: 512M of GTT memory ready.
[ 8.710229] radeon 0000:01:05.0: WB enabled
[ 8.710233] radeon 0000:01:05.0: fence driver on ring 0 use gpu addr 0x00000000a0000c00 and cpu addr 0xff865c00
[ 8.710236] radeon 0000:01:05.0: fence driver on ring 3 use gpu addr 0x00000000a0000c0c and cpu addr 0xff865c0c
[ 8.710252] [drm] radeon: irq initialized.
[ 8.710487] radeon 0000:01:05.0: setting latency timer to 64
[ 8.742756] [drm] radeon: power management initialized
[ 8.784950] fbcon: radeondrmfb (fb0) is primary device
[ 8.797593] radeon 0000:01:05.0: fb0: radeondrmfb frame buffer device
[ 8.797595] radeon 0000:01:05.0: registered panic notifier
[ 8.797663] [drm] Initialized radeon 2.33.0 20080528 for 0000:01:05.0 on minor 0