Re: MAX_USBFS_BUFFER_SIZE

[Greg KH]

On Wed, Mar 01, 2006 at 11:34:30PM +0100, Olivier Galibert wrote:
> On Wed, Mar 01, 2006 at 01:54:23PM -0800, Greg KH wrote:
> > On Wed, Mar 01, 2006 at 10:42:35PM +0100, Ren? Rebe wrote:
> > > So, queing alot URBs is the recommended way to sustain the bus? Allowing
> > > way bigger buffers will not be realistic?
> > 
> > 16Kb is "way big" in the USB scheme of things aready.  Look at the size
> > of your endpoint.  It's probably _very_ small compared to that.  So no,
> > larger buffer sizes is not realistic at all.
> 
> As a data point, I have traces of a scanner session including a
> download of a 26Mb binary image using 524288 bytes logical blocks
> physically transferred with 61440 bytes bulk_in frames.  Seems stable
> enough.  IIRC the scanner-side controller chip has some advanced
> buffering just to handle that kind of bandwidth.

That's impressive.  What are the endpoint sizes on the device that did
this?

thanks,

greg k-h
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