Re: [PATCH/RFC 5/5] usb: Add support for streams alloc/dealloc to devio.c

Hans Petter Selasky
2011-08-22T08:00:56Z

On Sunday 21 August 2011 12:18:34 Amit Blay wrote:
> Thanks Sarah, Hans for your comments,
>
> On Thu, August 18, 2011 3:47 pm, Sarah Sharp wrote:
> > Yes, I think this is the correct solution. Sorry for taking so long to
> > get back to you.
>
> OK, so I will go ahead with implementing this solution.
>
> > On Wed, Aug 17, 2011 at 09:06:03AM +0200, Hans Petter Selasky wrote:
> >> I would suggest overloading the "unsigned int pipe", instead of breaking
> >> existing API's by adding a new stream ID value. Also for LibUSB.
>
> The purposed solution will not break any existing API, by doing the
> following:
> a. Adding a new API for streams alloc/dealloc
> b. Adding a new API for submitting a URB which is stream capable (I will
> implement this in a separate patch).
>
> > I don't see this as a strong argument why we should arbitrarily limit a
> > new API. It's very hard to deprecate kernel to userspace API, so I
> > think we should do it right the first time. There are current
> > applications (like an SSD behind a UAS device) that need as many
> > concurrent streams in flight as possible, so I don't buy the argument
> > that there aren't current applications that need that many streams.
>
> I agree with Sarah.
> Hans, I appreciate your inputs. Please let me know if you see a good
> reason why not implementing the new APIs purposed above for streams
> allocation and usage. Otherwise I will go ahead with the implementation.

Hi Amit,

I think your suggestion is OK.

--HPS