From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Martin K. Petersen" Date: Wed, 21 Apr 2010 16:18:51 +0000 Subject: Re: System hangs when using USB 3.0 HD with on Ubuntu Message-Id: List-Id: References: In-Reply-To: (Alan Stern's message of "Wed, 21 Apr 2010 12:09:57 -0400 (EDT)") MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Alan Stern Cc: Luben Tuikov , Sarah Sharp , Jonas Schwertfeger , USB Storage List , Matthew Dharm , "" , Lennart Poettering , Douglas Gilbert , "" , Mark Lord , Sergei Shtylyov , James Bottomley , Kay Sievers , David Zeuthen , "" , "" >>>>> "Alan" = Alan Stern 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