I forgot to mention -- once a phase error is detected, the USB specification requires the host to issue a RESET to the device.
Matt
On Sat, Sep 23, 2006 at 02:53:05PM -0700, Matthew Dharm wrote:
> This sounds like the device is getting out of sync (commonly known as
> "phase error"). The host sent a command, but the device was not prepared
> to send data at the proper time, and indicated an error with a STALL.
>
> The proper response to a STALL at this point is to attempt to retrieve
> status, which is what happens. However, the device responds with data (not
> status).
>
> It is possible that an earlier error in the device left the bulk-in
> endpoint in a STALL condition (which is persistent). What was the result
> of last transaction to the bulk-in endpoint before this exchange you
> describe below?
>
> Matt
>
> On Sun, Sep 24, 2006 at 01:11:36AM +0530, Rupesh Kumar wrote:
> >
> > Hi All,
> >
> >
> >
> > I am having an embedded EHCI USB host controller on which i am using
> > linux-2.6.14
> >
> >
> >
> > When i am doing bulk file copys between many devices i am facing the
> > following problem.
> >
> >
> >
> > The following scenario is observed on the USB BUS Analyzer.
> >
> >
> >
> > 1. Bulk Out Transaction with (31 Bytes USBC Command) for some
> > endpoint.
> >
> > I am requesting 4K Data from device.
> >
> > 2. Then There are lot of Bulk IN/ Bulk OUTs to some other
> > endpoints(Other Devices).
> >
> > 3. Then When i am giving a IN to the first end point (For
> > which we transmitted a BULK OUT 31 Bytes)
> >
> > device is responding with a STALL..
> >
> > 4. After Clearing the HALT On the endpoint. with a clear
> > feature command
> >
> > 5. Then driver is asking for the CSW Status for which the
> > device is responding with 512 Bytes of Data.
> >
> >
> >
> > This is Causing a BABBLE Error (Expecting 13 Bytes of CSW but
> > the device responded with 512 bytes).
> >
> > Then the driver is issuing RESET to the device.
> >
> >
> >
> > Is it an acceptable condition.
> >
> > who is the culprit for the RESET.
> >
> >
> >
> > Regards
> >
> > Kumar.
>
> --
> Matthew Dharm Home: [EMAIL PROTECTED]
> Maintainer, Linux USB Mass Storage Driver
>
> G: Let me guess, you started on the 'net with AOL, right?
> C: WOW! d00d! U r leet!
> -- Greg and Customer
> User Friendly, 2/12/1999
--
Matthew Dharm Home: [EMAIL PROTECTED]
Maintainer, Linux USB Mass Storage Driver
C: Like the Furby?
DP: He gives me the creeps. Think the SPCA will take him?
-- Cobb and Dust Puppy
User Friendly, 1/2/1999
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