linux-kernel - [PATCH] PM: Add convenience macro to make switching to dev_pm

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Date:	Wed, 5 Aug 2009 22:05:13 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Albin Tonnerre <albin.tonnerre@...e-electrons.com>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Frans Pop <elendil@...net.nl>, linux-kernel@...r.kernel.org,
	Linux PM List <linux-pm@...ts.linux-foundation.org>,
	Daniel Mack <daniel@...aq.de>
Subject: [PATCH] PM: Add convenience macro to make switching to dev_pm_ops less error-prone

On Wednesday 05 August 2009, Rafael J. Wysocki wrote:
> On Wednesday 05 August 2009, Albin Tonnerre wrote:
> > On Tue, Aug 04, 2009 at 09:55:33PM -0700, Dmitry Torokhov wrote :
> > > On Tue, Aug 04, 2009 at 11:36:12AM +0200, Albin Tonnerre wrote:
> > > > In a number of cases, the .suspend, .freeze, .poweroff and .resume,
> > > > .thaw, .restore functions are identical. However, they all need to be
> > > > assigned to avoid regressionsm as the previous code called .suspend
> > > > resp. .resume in all those cases. SIMPLE_PM_OPS allows to deal with
> > > > this case.
> > 
> > 
> > > I'd much rather have conversions done with a bit more analysis now that
> > > our framework is more flexible and we can have specialized routines for
> > > hibernation and suspend.
> > 
> > I still think that even though they can, quite a number of drivers won't
> > /need/ to have different functions for this, but maybe I'm mistaken.
> > 
> > > Maybe we should try changing from run-time to build time warning so that
> > > users are not overly concerned with it?
> > 
> > I'm not sure that solves the problem. The fact is that even for developers, it's
> > easy to overlook that assiging only the .suspend and .resume fields is probably
> > a mistake.
> 
> I agree, so I'm going to take the patch.
> 
> I'll add a comment describing what the macro is for, though.

Strictly speaking, I'm going to add the appended patch to the linux-next
branch of the suspend-2.6 tree.

Thanks,
Rafael

---
From: Albin Tonnerre <albin.tonnerre@...e-electrons.com>
Subject: PM: Add convenience macro to make switching to dev_pm_ops less error-prone

In a number of cases, the .suspend, .freeze, .poweroff and .resume,
.thaw, .restore functions are identical. However, they all need to be
assigned to avoid regressionsm as the previous code called .suspend
resp. .resume in all those cases. SIMPLE_DEV_PM_OPS helps to deal
with this case.

[rjw: Changed the name of the macro and added the comment explaining its
 purpose.]

Signed-off-by: Albin Tonnerre <albin.tonnerre@...e-electrons.com>
Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
---
 include/linux/pm.h |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

Index: linux-2.6/include/linux/pm.h
===================================================================
--- linux-2.6.orig/include/linux/pm.h
+++ linux-2.6/include/linux/pm.h
@@ -184,6 +184,20 @@ struct dev_pm_ops {
 	int (*restore_noirq)(struct device *dev);
 };
 
+/*
+ * Use this if you want to use the same suspend and resume callbacks for suspend
+ * to RAM and hibernation.
+ */
+#define SIMPLE_DEV_PM_OPS(name, suspend_fn, resume_fn) \
+struct dev_pm_ops name = { \
+	.suspend = suspend_fn, \
+	.resume = resume_fn, \
+	.freeze = suspend_fn, \
+	.thaw = resume_fn, \
+	.poweroff = suspend_fn, \
+	.resume = resume_fn, \
+}
+
 /**
  * PM_EVENT_ messages
  *
--
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