Re: System hangs when using USB 3.0 HD with on Ubuntu

Martin K. Petersen
2010-04-21T16:18:51Z

>>>>> "Alan" == Alan Stern <stern@rowland.harvard.edu> writes:

I'm guessing Doug is out today because he didn't forward the note
below. Just passing the info along...

>> It is needed by the transport protocol(s).

Alan> I don't understand; can you explain more fully? Which transport
Alan> protocol(s) need to use the Sector Count? The USB transport
Alan> protocol doesn't; it encodes the transfer length in a wrapper.
Alan> The bridge chip should interpret the wrapper instead of looking
Alan> inside the SAT command.

Doug posted to the T10 list and here's what Jim Hatfield from Seagate
responded:

For ATA (SATA or PATA), the Count field should NEVER be zero,
because neither interface supports zero-length data transfer for
any protocol (dma, pio, etc).

In ATA, 'N/A' is defined the way it is because there are some
ancient implementations for which there are vendor specific
differences.

--
Martin K. Petersen Oracle Linux Engineering