[wdmaudiodev] Re: MaxTransferSize and Control Endpoint
- From: Tim Roberts <timr@xxxxxxxxx>
- To: wdmaudiodev@xxxxxxxxxxxxx
- Date: Mon, 22 Oct 2007 10:59:03 -0700
My apologies to those who receive this twice. The original message I
replied to had been marked by SpamAssassin, and I forgot to remove the
marking from the subject line.
On Wed, Oct 10, 2007 at 07:36:41AM -0700, wade wrote:
>
> Does anyone know if there is a way to set the MaxTransferSize for the
> control Endpoint using USBD? I'm successfully selecting an
> interface with the desired MaxTransferSize but when I do a
> Control-Write with a MaxTransferSize-sized packet I'm get an int3 in
> the IOCallDriver() call and a STATUS_INVALID_PARAMETER return from
> the call.
>
> The MaxTransferSize of the selected interface is 8204 bytes but I'm
> only able to send about 4k without the int3.
I don't know what you mean by that sentence. Interfaces do not have
a max transfer size. Pipes have a MaximumTransferSize, although Windows
XP ignores it.
However:
http://support.microsoft.com/kb/832430
The control endpoint has a maximum transfer size of 4k, and there's
nothing you can do to change that. Remember that the control endpoint
on a high-speed device can only transfer 64 bytes at a time, so even
a 4k transfer is a lot of consecutive packets.
You will have to chop it into smaller pieces on your own.
--
Tim Roberts, timr@xxxxxxxxx
Providenza & Boeklheide, Inc.
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