Author Topic: USB Mass Storage Reset Request  (Read 4822 times)

ember

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USB Mass Storage Reset Request
« on: August 17, 2014, 12:28:16 pm »
Hi Jan,
         I am working on USB msc device side. What should be the response from the device when the host raises a Bulk only mass storage reset request. ? Apart from the response what should it do in the reset request handler.
It was mentioned like
"The host shall send this request via the default pipe to the device. The device shall preserve the value of its bulk
data toggle bits and endpoint STALL conditions despite the Bulk-Only Mass Storage Reset.
The device shall NAK the status stage of the device request until the Bulk-Only Mass Storage Reset is complete."
But i am not clear about this..

Please elaborate :)

Thanks
Ember.

Jan Axelson

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Re: USB Mass Storage Reset Request
« Reply #1 on: August 17, 2014, 09:27:53 pm »
On receiving this request:

Do not reset the bulk endpoints' data toggle bits.

Do not change the STALL condition of endpoints. (See USB 2.0 spec, 8.4.5)

In the status stage of the request, do not return a zero-length data packet until the bulk IN endpoint is read to receive a CBW  (unless the endpoint is in the STALL condition).