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
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C: WOW! d00d! U r leet!
-- Greg and Customer
User Friendly, 2/12/1999
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