From mboxrd@z Thu Jan 1 00:00:00 1970 From: Aaron Lu Subject: Re: REQ_PM vs REQ_TYPE_PM_RESUME Date: Wed, 08 Jan 2014 10:11:52 +0800 Message-ID: <52CCB3E8.5010101@intel.com> References: <1387236657-4852-1-git-send-email-psusi@ubuntu.com> <52CA1191.8060804@ubuntu.com> <52CA5CF4.2080708@codeaurora.org> <52CA744F.2080609@intel.com> <52CAC067.20601@ubuntu.com> <52CBB188.2080707@intel.com> <52CC1422.1020101@ubuntu.com> <52CCA3CF.5050308@intel.com> <52CCA6E3.2090400@ubuntu.com> <52CCAAA7.4070104@intel.com> <52CCAF8C.7040407@ubuntu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <52CCAF8C.7040407@ubuntu.com> Sender: linux-ide-owner@vger.kernel.org To: Phillip Susi , Sujit Reddy Thumma Cc: todd.e.brandt@linux.intel.com, tj@kernel.org, JBottomley@parallels.com, linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org, Alan Stern , Linux-pm mailing list , "Rafael J. Wysocki" List-Id: linux-pm@vger.kernel.org On 01/08/2014 09:53 AM, Phillip Susi wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA512 > > On 01/07/2014 08:32 PM, Aaron Lu wrote: >> The ATA and SCSI devices are all resumed in my patches, notice >> there is a single pm_request_resume call in both ATA and SCSI's >> system resume callback, so the runtime status and the disk's state >> is synced. The pm_request_resume call is asynchronous to the system >> resume, so it doesn't block system resume. >> >> But I see your point, my patch will not achieve that, it can only >> speed up S3 for a typical PC with a traditional disk. I can omit >> the pm_request_resume call in the system resume callback, but then >> if the disk is spun up by itself, then the runtime status indeed >> doesn't reflect the actual state. I suppose for SATA controllers >> that support Staggered Spin-up wouldn't do this? > > Ahh, yes, the point of my patches was to avoid waking a disk at all if > possible, and avoid blocking on it otherwise. Todd Brandt's patches > just backgrounded the resume. > > As far as I can tell, the AHCI staggered spinup feature is only a hint > to the libata driver that it should not probe all disks in parallel. I thought that feature is used to control if a disk should be spun up once powered from the host side. > The way to get an ATA disk to not spin itself up is by enabling the > Power on in Standby feature, either through hdparm, or via a jumper, Too bad for a jumper, that's beyond our control. And about the hdparm, does the setting survive a power cycle?