Re: Disable the suspend mode of USB host

Tech-Archive recommends: Repair Windows Errors & Optimize Windows Performance

From: Frank Chen (fchen_at_tekscan.com)
Date: 08/17/04 

Date: Tue, 17 Aug 2004 15:21:12 -0400

Hi Seung,

Thanks for the help.

There is no entry for the HCD1: under anywhere in
HKLM\SYSTEM\CurrentControlSet\Control\Power\State.

I tried for adding HCD1: = 0 at both
HKLM\SYSTEM\CurrentControlSet\Control\Power\State\UserIdle\ and
HKLM\SYSTEM\CurrentControlSet\Control\Power\State. They won't work.

Could you please specify it a little more about it?

Thanks,
Frank

"Seung Yi" <seungyi@codetelligence_NOSPAMMERS_.com> wrote in message
news:OKliEJIhEHA.3988@tk2msftngp13.phx.gbl...
> Frank Chen wrote:
> > I found this discussion from the microsoft.public.windowsce.embedded
group
> > through google search and it is related to our development problems.
> >
> > When I plug in the USB device to the Pocket PC running Windows CE.net
4.2,
> > at the first the USB device gets enumerated correctly, than after 2 or 3
> > seconds, it seems going into suspend mode. When there are attempt trying
to
> > write or read from the USB device, the device LED indicating that the it
> > resumed while the read data is not correct. As soon as the data IO
finished,
> > it goes SUSPEND mode immediately.
> >
> > How can I disable the USB bus suspend function to my device so that the
> > device is always ready for the data IO?
> >
> > Is any way to ask the USB bus return to power FULL ON mode before the
USB
> > device doing the data IO?
> >
> >
> >
> > We are using eV++ 4.0 for developing the USB driver and CE application
even
> > though we have a license of PB 4.1
> >
> > Thank you for the help,
> >
> > Frank Chen
> >
>
> -------------------------------------------------------------------------- 

--
> >
> > Are you talking about USB bus states or Windows CE power states. I
assume
> >
> > you mean CE power states.
> >
> > If your client driver exposes a stream interface (by calling
> >
> > ActivateDevice() on itself) it will receive PowerUp()/PowerDown()
callbacks
> >
> > just like any other driver. I'm not sure what's in the CE 3.0
distribution,
> >
> > but the USB printer driver does this -- check out USBDeviceAttach() in
> >
> > public\common\oak\drivers\usb\class\printer (the path may be slightly
> >
> > different in 3.0).
> >
> > Note that the operations you can carry out in a device driver are
greatly
> >
> > restricted in power callbacks. In particular, you can't issue USB
> >
> > transfers, write the registry, or make most API calls. Also, your device
is
> >
> > likely to get unloaded and reloaded as soon as the system resumes.
> >
> > Hope this helps,
> >
> > Andrew Pearson
> >
> > --
> >
> > To reply directly, remove "online." from my email address.
> >
> > This posting is provided "AS IS" with no warranties, and confers no
rights.
> >
> >
> >
> >
> >
> > "k.kasama" <XBN00421@nifty.com> wrote in message
> >
> > news:090701c29d08$feb1a770$d5f82ecf@TK2MSFTNGXA12...
> >
> >
> >>I am developping USB client driver for Windows CE3.0.
> >
> >
> >>Is there method to detect a transition from On/Idle state
> >
> >
> >>to Suspend state?
> >
> >
> >
> >>Regards,
> >
> >
> >
> >
> >
> >
> >
>
> You can check the system - to- power state mapping in the registery and
> check to see if the USB host controller has a specific device power
> state mapping (it would have an entry for something like HCD1:).
>
> See: HKLM\SYSTEM\CurrentControlSet\Control\Power\State
>
>
>   I am assuming that the 2-3 second suspen, may be a result of user Idle
> system power state causing the power manager to broadcast a power state
> lower than D0 to devices in particular the USB host controller.  You
> could experiment by forcing power state mappings to keep HCD1: at D0 all
> the time.
>
> As for an API, there is no USBD API in CE.4.2 to tell the host
> controller to keep the USB bus from entering suspend.  In CE 5.0,
> drivers can selectively suspend/resume their device.
>
>
>
>
>
> -- 
> Seung Yi
> Senior Engineer
> Codetelligence, Inc.
> Web   : www.codetelligence.com

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