* [9fans] icky specs
@ 2004-07-09 12:36 Brantley Coile
2004-07-09 13:23 ` Nigel Roles
0 siblings, 1 reply; 2+ messages in thread
From: Brantley Coile @ 2004-07-09 12:36 UTC (permalink / raw)
To: 9fans
Anyone have a pointer to where on the web I can
get a copy of the *CHI specs?
Brantley
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [9fans] icky specs
2004-07-09 12:36 [9fans] icky specs Brantley Coile
@ 2004-07-09 13:23 ` Nigel Roles
0 siblings, 0 replies; 2+ messages in thread
From: Nigel Roles @ 2004-07-09 13:23 UTC (permalink / raw)
To: Fans of the OS Plan 9 from Bell Labs
Brantley Coile wrote:
>Anyone have a pointer to where on the web I can
>get a copy of the *CHI specs?
>
> Brantley
>
>
>
http://www.usb.org/developers/docs/
Well well, I took a cursory look at EHCI, and it's an Intel spec.,
which admits to fixing a lot of USB 1.1 host controller
issues (i.e. those specific to UHCI). Most of the changes
relate to reducing the overhead I/O load. This is achieved
by allowing descriptors to reference more and bigger
buffers.
(UHCI or OHCI) reads in-memory descriptors to decide
what to do for each endpoint. These are chained and there
can be as many of them as the driver designer chooses.
It always worried me that there must
be a limit as to how many of these can be walked before
the chip runs out of time to make a decision.
Evidently, at 480mbps, it became a real issue.
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