Comment 101 for bug 564376

(In reply to comment #50)
> I played a bit with power_profile settings and it turns our that whenever
> profile is set to high, mid, sound stuttering is pronounced. Yet, once set to
> low, stuttering is gone (or unnoticeable).
> If anyone wants to try (adjust path to suit your hardware):
> echo low > /sys/class/drm/card0/device/power_profile
> Then the actual frequency can be verified by:
> cat /sys/kernel/debug/dri/0/radeon_pm_info

Confirming this on ATI X1400 mobile, Ubuntu 11.04 x86. When using the "low" power profile, audio stuttering/crackling is much less prevalent (or maybe not even noticable) in Youtube fullscreen vids. Using the "high" setting results in definite audio crackling when switching to fullscreen. This is with the very latest Flashplayer 11 beta for Linux released today.

On my card, low setting results in:
# cat /sys/kernel/debug/dri/0/radeon_pm_info
default engine clock: 392000 kHz
current engine clock: 128250 kHz
default memory clock: 350000 kHz
current memory clock: 135000 kHz
PCIE lanes: 1

High setting gives:
# cat /sys/kernel/debug/dri/0/radeon_pm_info
default engine clock: 392000 kHz
current engine clock: 391500 kHz
default memory clock: 350000 kHz
current memory clock: 342000 kHz
PCIE lanes: 0

There's a difference not only in board frequencies, but also the PCIE lanes number (0 means full throttle, or is "more performant" than 1 I guess ??).