From mboxrd@z Thu Jan  1 00:00:00 1970
From: Oliver Neukum <oneukum@suse.de>
Subject: Re: Disk spin-up optimization during system resume
Date: Fri, 17 Jan 2014 11:16:49 +0100
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References: <Pine.LNX.4.44L0.1401161125080.1109-100000@iolanthe.rowland.org>
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To: Alan Stern <stern@rowland.harvard.edu>
Cc: Todd E Brandt <todd.e.brandt@linux.intel.com>, Phillip Susi <psusi@ubuntu.com>, Aaron Lu <aaron.lu@intel.com>, Tejun Heo <tj@kernel.org>, SCSI development list <linux-scsi@vger.kernel.org>

On Thu, 2014-01-16 at 11:59 -0500, Alan Stern wrote:
> Since the START-STOP and TEST UNIT READY (or REQUEST SENSE or
> whatever)  
> commands are likely to take a long time, they should all be carried
> out
> asynchronously with respect to the resume procedure.  I don't know
> what
> the best way is to implement this.  But it is important to guarantee
> that in the RPM_ACTIVE case, the START-STOP command gets sent to the
> disk before any other commands.  (This isn't an issue in the 
> RPM_SUSPENDED case, as the block layer will prevent requests being 
> sent out unless they have the REQ_PM flag set.)
> 
> Does this plan sound reasonable to everyone?  Are there important
> aspects I haven't considered (such as interactions between the SCSI
> and
> ATA layers)?

The START-STOP may result in an error. What do you do in that case?

	Regards
		Oliver