Messages in this thread | | | From | Hans Petter Selasky <> | Subject | Re: [PATCH/RFC 5/5] usb: Add support for streams alloc/dealloc to devio.c | Date | Wed, 17 Aug 2011 09:06:03 +0200 |
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On Wednesday 27 July 2011 08:21:35 Amit Blay wrote: > Hi Sarah, > > A gentle reminder, can you please take a look at the proposed solution > below for stream alloc/dealloc in devio.c? I responded to your comments > about the original patch.
Hi,
I'm looking into implementing USB 3.0 streams support for FreeBSD and would like to have a solution in Linux which is not too far apart, also regarding API's for userspace.
I would suggest overloading the "unsigned int pipe", instead of breaking existing API's by adding a new stream ID value. Also for LibUSB.
./linux/usb.h: unsigned int pipe; /* (in) pipe information */
As per definition there are 15 bits available for "pipe". I think it is not important to support more than 255 streams in the first go, hence I see no real applications that would benefit from that many streams yet.
#define usb_pipeendpoint(pipe) (((pipe) >> 15) & 0xf)
Then I suggest a new function/IOCTL in libusb which can be used to switch on/off streams on a given endpoint. This is something which would need to be done before submitting any URB's on that endpoint. And would be similar to the clear-stall case.
If an URB is submitted on a stream when streams are disabled then it should just fail and vice versa.
--HPS
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