Re: Implementing isochronous transfers in hw/hcd-ohci.c

[Gerd Hoffmann]

On Thu, Sep 09, 2021 at 05:06:17PM -0400, Programmingkid wrote:
> Hi Gerd,
> 
> Howard and I were talking about USB audio problems with Mac OS guests. We 
> think the issue might be with frames being sent to the USB audio card too 
> soon. My guess is only one frame is suppose to be transmitted every 1 
> millisecond. I was also reading the todo notes in the file hw/hcd-ohci.c. 
> This is what it says:
> 
>  * TODO:
>  *  o Isochronous transfers
>  *  o Allocate bandwidth in frames properly
>  *  o Disable timers when nothing needs to be done, or remove timer usage
>  *    all together.
>  *  o BIOS work to boot from USB storage
> */
> 
> Do you think implementing isochronous transfers would fix the audio problems 
> Mac OS guest are experiencing?

Most likely yes, audio devices typically use iso endpints.

take care,
  Gerd