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 11:34:25 -0500 Message-ID: <52CECF91.10206@ubuntu.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-scsi-owner@vger.kernel.org To: 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, Linux-pm mailing list , "Rafael J. Wysocki" List-Id: linux-pm@vger.kernel.org -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 1/9/2014 11:14 AM, Alan Stern wrote: > That's true, but it isn't a problem. We know that requests with > REQ_PM are sent only at certain, controlled times. In particular, > the only time such a request would be sent while the disk is > RPM_SUSPENDED is during a system resume. Yes, but if the disk and port were both already RPM_SUSPENDED when the system was suspended, and so the port is still RPM_SUSPENDED when the disk's system resume method is called, then it can't communicate with the disk. >> We need to put the device into one of the transitioning states >> to block other IO, without allowing the port to suspend. > > No, we only need to make sure that the port doesn't go into runtime > suspend while we carry out the "is the disk spinning" test. Well how else do you do that other than with the transition states? -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.17 (MingW32) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBAgAGBQJSzs+RAAoJEI5FoCIzSKrw1KoH+gJ4c1iXqOUUqJfF2xoxrF6k Fv3KyTNMn8Y9RF12o5OlfQHwPkwhplIR7uBd5agnd9cXR2owRVLgAE34/ggEEOOq NgaRwfNBbD3Q83I/6aEZ7C7A0wbWyrA+w2aaBIe5RzTslH3IYcePZvnKUZuG+/0A rAR/IVyNL5e6JDPgvSkx7/LmxLVb3M4NkYeCMHvl8Gmg+bvg2S+R3TAcUTvRzRv4 gwtkbYGkyS/NmXc86Vi7Z2pOcIyZT3T0CyzlSqAIjljYSFJbzY+PRP4D4gAOXqyd vqrg+PtxUYlQ0POdYRo0TtCe2N5nk4RI3jwiyD0U1/GFgcY/uNNJOtPaiQOLxOU= =cMp1 -----END PGP SIGNATURE-----