Re: [RFC PATCH] scsi: sr: support runtime pm

From: Alan Stern <stern@rowland.harvard.edu>
To: Aaron Lu <aaron.lu@intel.com>
Cc: Oliver Neukum <oneukum@suse.de>,
	Julian Calaby <julian.calaby@gmail.com>,
	James Bottomley <James.Bottomley@HansenPartnership.com>,
	Jeff Garzik <jgarzik@pobox.com>,
	"Rafael J. Wysocki" <rjw@sisk.pl>, Tejun Heo <tj@kernel.org>,
	Aaron Lu <aaron.lwe@gmail.com>, Jeff Wu <jeff.wu@amd.com>,
	linux-ide@vger.kernel.org, linux-pm@vger.kernel.org,
	linux-scsi@vger.kernel.org, linux-acpi@vger.kernel.org
Subject: Re: [RFC PATCH] scsi: sr: support runtime pm
Date: Mon, 21 Jan 2013 11:59:06 -0500 (EST)	[thread overview]
Message-ID: <Pine.LNX.4.44L0.1301211157530.19920-100000@netrider.rowland.org> (raw)
In-Reply-To: <20130121093707.GB11010@aaronlu.sh.intel.com>

On Mon, 21 Jan 2013, Aaron Lu wrote:

> On Sat, Jan 19, 2013 at 01:46:15PM -0500, Alan Stern wrote:
> > On Sat, 19 Jan 2013, Aaron Lu wrote:
> > > I don't think we should drop such support.
> > > And the safest way to avoid such break is we refine the suspend
> > > condition for ODD, and using what ZPODD defined condition isn't that
> > > bad to me:
> > > - for tray type, no media inside and tray close;
> > > - for slot type, no media inside.
> > > While whether tray is closed or not may not be that important, but at
> > > least we should make sure there is no media inside.
> > > 
> > > Thoughts?
> > 
> > That sounds reasonable to me, at least as a first step.  If people want 
> > their CD drive to suspend, they can eject the disc.
> 
> Here is an updated patch to address the problem, please review, thanks.
> 
> Changes to v13:
> - Add PM get/put pair functions to all the block device operation
>   functions; Move the existing PM get/put pair functions in
>   sr_check_events to sr_block_check_events;
> - Add sr_runtime_suspend, it will check if there is media inside and if
>   yes, avoid suspend.
> 
> From 378bf55810a1118ede481f45132b5c39af891d23 Mon Sep 17 00:00:00 2001
> From: Aaron Lu <aaron.lu@intel.com>
> Date: Wed, 26 Sep 2012 15:14:56 +0800
> Subject: [RFC PATCH] scsi: sr: support runtime pm
> 
> This patch adds runtime pm support for sr.
> 
> It did this by increasing the runtime usage_count of the device when
> its block device is accessed. And decreasing the runtime usage_count
> of the device when the access is done.
> 
> The idea is discussed here:
> http://thread.gmane.org/gmane.linux.acpi.devel/55243/focus=52703
> and here:
> http://thread.gmane.org/gmane.linux.ide/53665/focus=58836
> 
> Signed-off-by: Aaron Lu <aaron.lu@intel.com>

This looks good now.  When you submit the patch, you might want to 
mention the restriction about no media being present in the changelog 
entry.

Acked-by: Alan Stern <stern@rowland.harvard.edu>