Re: OvlK_Wait() fails for iso EP poll rate >1ms

Greetings,

This is a windows limitation.  For high speed ISO, bInterval can be only 
1,2,3, or 4.
  http://msdn.microsoft.com/en-us/library/windows/hardware/hh406225%28v=vs.85%29.aspx

Back in early beta I standardize on "INT, UINT, PINT, PUINT" for 32bit 
types.  Understand that long's are also 32 bit types in C/C++.  
Microsoft has a habit of making a mess with all of these.

Regards,
Travis

On 8/22/2014 6:47 AM, Børge Strand-Bergesen wrote:
> Hi guys,
>
> I'm working on a USB ASIO driver based on libusbK. It uses an
> isochronous IN endpont for a feedback from the Device. Descriptor dump
> is attached.
>
> The ASIO driver fails when the IN endpoint's poll rate becomes >1ms.
> (See w5.txt line 220.) Rapid polling isn't needed in the application,
> and I'd like to make it slower.
>
> Values of 4 and below work as expected in libusbK and mimic what I see
> in Linux. 4 gives 1ms polling rate, 3->1/2ms, 2->1/4ms etc. But on
> Linux I also have 5->2ms, 6->4ms, 7->8ms, 8->16ms. (Testing on OS X
> roughly tracks what I see on Linux, but with fewer transitions. There
> may be bugs in the descriptors which cause libusbK and OS X to
> misunderstand them in different ways, where Linux seems to be OK.)
>
> What seems to happen is a failure in OvlK_Wait(). When called,
> GetLastErrorInternal(); returns 00000057h.
>
> The calling code is line 138 of:
> https://github.com/nikkov/Win-Widget/blob/experimental/uaclib/UsbDevice.h
>
> I use the latest libusbK 3.0.7.0 which I downloaded, linked to and
> installed today. The built .dll is a 32-bit application. My system is
> Win7-64.
>
> One thing I notice is that OvlK_Wait() parameter TransferredLength is
> now PUINT. In the ASIO driver code it was PULONG for a while, but I
> believe I have fixed that in all of the code now.
>
> I hope you can help me out with this issue. I hope device performance
> will be better on weaker computers with slower polling.
>
> Let me know if you need more details about my system.
>
>
> Thanks,
> Børge
>
>
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