From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Martin K. Petersen" <martin.petersen@oracle.com>
Subject: Re: System hangs when using USB 3.0 HD with on Ubuntu
Date: Wed, 21 Apr 2010 12:18:51 -0400
Message-ID: <yq1fx2owzh0.fsf@sermon.lab.mkp.net>
References: <Pine.LNX.4.44L0.1004211205560.1728-100000@iolanthe.rowland.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Return-path: <linux-hotplug-owner@vger.kernel.org>
In-Reply-To: <Pine.LNX.4.44L0.1004211205560.1728-100000@iolanthe.rowland.org>
	(Alan Stern's message of "Wed, 21 Apr 2010 12:09:57 -0400 (EDT)")
Sender: linux-hotplug-owner@vger.kernel.org
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Luben Tuikov <ltuikov@yahoo.com>, Sarah Sharp <sarah.a.sharp@linux.intel.com>, Jonas Schwertfeger <jschwertfeger@gmail.com>, USB Storage List <usb-storage@lists.one-eyed-alien.net>, Matthew Dharm <mdharm-usb@one-eyed-alien.net>, "<linux-scsi@vger.kernel.org>" <linux-scsi@vger.kernel.org>, Lennart Poettering <lennart@poettering.net>, Douglas Gilbert <dgilbert@interlog.com>, "<Dinh.Nguyen@freescale.com>" <Dinh.Nguyen@freescale.com>, Mark Lord <mlord@pobox.com>, Sergei Shtylyov <sshtylyov@mvista.com>, James Bottomley <James.Bottomley@suse.de>, Kay Sievers <kay.sievers@vrfy.org>, David Zeuthen <david@fubar.dk>, "<linux-hotplug@vger.kernel.org>" <linux-hotplug@vger.kernel.org>, "<linux-usb@vger.kernel.org>" <linux-usb@vger.kernel.org>
List-Id: linux-scsi@vger.kernel.org

>>>>> "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