Re: USB host speed when using both ehci and ohci

Tech-Archive recommends: Fix windows errors by optimizing your registry

You need both [UO]HCI and EHCI.
As you described, low & full speed device won't work without [UO]HCI
controller.
For details, please refer USB 2.0 spec.

Some reason, your High speed device connected to OHCI.
There may be couple of reasons like Host controller issue, Host controller
driver issue, electrical issue like noise and others.

Bottom line is you need both OHCI and EHCI driver for USB 2.0 Host controller.

"Andy Purcell" wrote:

Hello,

Thanks for responding.
Our h/w does support both OHCI and EHCI, i.e., it has both OHCI and EHCI
registers.
If I put just EHCI in, and there is no driver for the OHCI hardware, and if
just a mouse is plugged in, it does not work.
So it seems I must put both OHCI and EHCI in.
So the question remains - is the registry "Order"=3 for EHCI and "Order"=2
for OHCI a robust way to make sure EHCI is used for 480 Mbps devices and
OHCI is used for 12 Mbps devices? Experimentally it works, but I would like
to hear from an expert.

Thanks


"Michel Verhagen [eMVP]" <myfirstname@xxxxxxxxxxxxx> wrote in message
news:%23szzLVy4JHA.5728@xxxxxxxxxxxxxxxxxxxxxxx
You put in either EHCI -or- OHCI, depending on what is supported by your
chip. Apparently your chipset supports both (??!), but you clearly want
the faster EHCI, so just put EHCI in there.

Good luck,

Michel Verhagen, eMVP
Check out my blog: http://GuruCE.com/blog

GuruCE
Microsoft Embedded Partner
http://GuruCE.com
Consultancy, training and development services.

Andy Purcell wrote:
My problem is that if I include both ohci and ehci DLL's in my image, and
both drivers have the same "Order" field in the registry, ohci is used
for
communicating to a high-speed peripheral. Transfer rates occur at ohci 12
Mbps and not at ehci 480 Mbps.

This is not optimal.

I did an experiment and changed the "Order" field in the ehci registry
file
and now ehci is used to talk to my high speed usb peripheral.

Is this a robust solution or must I do something else ?

Thanks





.

Relevant Pages

  • Re: USB EHCI & OHCI drivers on Linux
    ... >We are planning to port the USB host controller driver from linux to ... >controller to work in EHCI mode? ... in simple words, is the OHCI ... >implementation subset of EHCI implementation? ...
    (comp.arch.embedded)
  • Re: USB 2.0 problems digging me in deeper
    ... > since you see an EHCI entry in device manager. ... > Each USB host controller has one root hub and multiple ports. ... If you plug in a low or full speed device a UHCI ...
    (microsoft.public.windowsxp.help_and_support)
  • Re: OHCI root_port_reset() deadly loop...
    ... What I have here are two NEC OHCI USB interfaces and one NEC EHCI ... HUB Port 1: OHCI #1, ...
    (Linux-Kernel)
  • Re: PCI USB2 Controller not recognising all ports
    ... > front-mounts I don't wish to install. ... when you plug in a usb2.0 device, ehci controller will claim it. ... You should get usba10_ohci driver instead ohci ...
    (comp.unix.solaris)
  • Re: Cruel and unusual problems with Proliant ML350
    ... devices is routed to irq 29: bce, ciss, ohci and ehci. ... Perl gives 43 and Python ... gives "42 monkeys1 snake", when the answer is clearly "41 monkeys ...
    (freebsd-stable)