USB isochronous traffic with Rasberry Pi [WAS: Re: USB audio device on Raspberry Pi]

[Hans Petter Selasky]

On 05/05/14 17:51, Adrian Chadd wrote:
> On 5 May 2014 08:35, Ian Lepore <ian at freebsd.org> wrote:
>
>> Oh never mind, I just noticed you said KTR, not printf.
>
> Heh.
>
> That's why I like KTR.
>
> I bet some devices dislike you doing the "read registers all the time"
> dance. Espeically if they're on an ISA bus where it's really expensive
> to do things. But yes, your point is pretty spot on.
>

Hi,

I've made another patch to reduce the number of interrupts generated by 
the DWC OTG in host mode:

http://svnweb.freebsd.org/changeset/base/265427

Still it is loosing service intervals at fixed rate 8K/second.

I added to DELAY():

if (!cold)
	return;

It made no difference.

I also tried to set INTR_PRIO_TTY instead of XXX_BIO.

No difference either.

I'll do some more checking later today.

--HPS