From mboxrd@z Thu Jan 1 00:00:00 1970 From: Phillip Susi Subject: Re: REQ_PM vs REQ_TYPE_PM_RESUME Date: Thu, 09 Jan 2014 14:20:44 -0500 Message-ID: <52CEF68C.40703@ubuntu.com> References: <52CC1FF2.1020301@ubuntu.com> <52CEEAA1.2010904@interlog.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.120]:58243 "EHLO cdptpa-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752547AbaAITUq (ORCPT ); Thu, 9 Jan 2014 14:20:46 -0500 In-Reply-To: <52CEEAA1.2010904@interlog.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: dgilbert@interlog.com, Alan Stern Cc: Aaron Lu , Sujit Reddy Thumma , todd.e.brandt@linux.intel.com, tj@kernel.org, JBottomley@parallels.com, linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 1/9/2014 1:29 PM, Douglas Gilbert wrote: > When REQUEST SENSE had its original semantics, TEST UNIT READY was > the only game in town for monitoring power management. From my > reading of spc4r36n.pdf section 5.1.2 "Important commands for all > SCSI device servers" TEST UNIT READY should be called before > REQUEST SENSE during device initialization (including resume). If > the responses to TEST UNIT READY and REQUEST SENSE contradict then > the former is correct. I don't see language there remotely like that. How did you arrive at this conclusion? > There are SCSI devices out caught in that transition. For example > with sg_format I monitor progress with either TEST UNIT READY or > REQUEST SENSE, defaulting to the former. [Progress indication is > another new role for REQUEST SENSE.] > > Note that the billion or so USB keys out there that say that they > comply with SCSI-2 should respond to a REQUEST SENSE with its > original semantics. Then they will return 0/0/0, so we will assume they are up and running, which is correct. SPC-2 is coming up on 13 years old and listed this usage for REQUEST SENSE. Are there any actual disk drives out there ( and still in use ) that return 0/0/0 when in the stopped state? I can't imagine there would be. > The ATA REQUEST SENSE DATA EXT command refers to the SPC-4 > "standard" (not yet it ain't) which is naturally the new SCSI > semantics of REQUEST SENSE. I believe the ATA REQUEST SENSE DATA > EXT command is a relatively new ATA command so it does not carry > the historical baggage of its SCSI counterpart. It is also only for ATAPI devices. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.17 (MingW32) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBAgAGBQJSzvaMAAoJEI5FoCIzSKrwcxIH/3Y7DdnXr6Fj9MiWs/Hn2kte EZVkHbj5jN4/OdKj3gnR3BK8gjrA7AEtbD3J6g7zJSj50UM1EA5RqMYAutZQkvYk UsKNuV+qIcN3OpSltAGK5TQPGUo2M9apcYuy9NKTZEaWI9dXejGJ/2GitxYXO35H drsTNlzEErnQvJwBhEYq6+rtferv7/vdZOljSGM1pP48gK0IWz+r2cwXxojkUvk1 lsiU97BxHCVNJc7kHmKVzBw0JV4R2mrtI/I/bE/VZzeljvjA9fNoXqdQxFU1RPDT PNLHBecjgbDlc70l1CNKNc4ApqBDSYg9SwBtG1nCa36MLgLoN1ZDEatzqT9IdYw= =qsZP -----END PGP SIGNATURE-----