lkml.org 
[lkml]   [2008]   [Jan]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [linux-usb-devel] [PATCH] : Allow embedded developers USB options normally reserved for OTG
Date
On Wednesday 02 January 2008, Alan Stern wrote:
>
> > The transaction translators in external high speed hubs require
> > hosts to issue particular USB transactions.  If the host controller
> > doesn't implement the that split transaction support, then it won't
> > be supporting external hubs.
>
> So in theory one could connect a high-speed hub to such a host
> controller and expect it to communicate with high-speed devices.  So
> long as no full- or low-speed devices are added there wouldn't be any
> split transactions.  It wouldn't be USB-2.0 compliant but it should
> still work.

Yes ...

But that would be a nightmare in terms of support calls. Take
two USB trees, and swap the hub ... suddenly one of the downstream
devices (the full speed one) starts (or stops!) working! That's
not the sort of issue any support line wants to cope with on a
day-to-day basis.

The accounting for those products is often along the lines of:
if you got a support call, you didn't profit from that sale.
(And from the user perspective it's just a PITA and waste of
time.) So *every* confusion like that one gets removed.

- Dave
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2008-01-03 04:53    [W:0.197 / U:0.900 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site