Hello

I have a z96js asus laptop, running Kalyway 10.5.2 and everything is good.

My graphics card is ATI radeon mobility x1600 and it is working fine with QE/CI enabled at full resolution.

And I am using an USB sound card.

The problem:

If there is some sort of screen update, there are bad glitches in audio. I know this is at driver level, because there is no big CPU load or something, and audio applications record to disk just fine. The glitches are just sent to the speakers.

If I disable QE and CI, the glitches disappear, but now the video is bad, and I still experience problems with OpenGL applications and fullscreen videos.

I'm thinking, there MUST be a way around without disabling QE and CI on my display but how... I have some stuff in my mind to try but don't know how to make them happen.

Is there any way to tweak PCI latency timers in OSX? Maybe giving lower priority to display card can fix the issue. 

Oh and here is my USB controller as listed in System info:

USB Bus:

  Host Controller Location: Built In USB
  Host Controller Driver: AppleUSBUHCI
  PCI Device ID: 0x27c8
  PCI Revision ID: 0x0002
  PCI Vendor ID: 0x8086
  Bus Number: 0x1d



Maybe the USB driver is incorrect... Is there any other drivers/fixes to try?

This is bothering me very much, any suggestions to try from more experienced hackers will be really appreciated.

PS: to disable QE/CI, I write this to console:

sudo defaults write /Library/Preferences/com.apple.windowserver GLCompositor -dict tileHeight -int 0 tileWidth -int 0

How can I see other values to be tweaked for GLCompositor, other than tileHeight and tileWidth? Are they documented somewhere? I'd like to try different settings.

Thanks!

Ok I have solved the issue as follows:

Somehow, the low speed usb bus controller driver(even if all your busses are 2.0 capable) freaks out when there is graphics activity. To make it work, buy a cheapo usb 2.0 hub and connect your sound card to that(even if your sound card is for usb1.1). And enjoy glitch-free sound...

(with this system, my fast-track pro stops responding if a program tries to change the system sampling rate. To avoid it, simply uninstall the drivers and let your device work in class compliant mode(untested) or use jackosx with a fixed samplingrate and route all your audio to jackrouter from sound settings)