linux-kernel - Re: [PATCH 1/5] PM: Make the initcall_debug style timing for suspend/resume complete

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Message-ID: <Pine.LNX.4.44L0.0912211612340.3328-100000@iolanthe.rowland.org>
Date:	Mon, 21 Dec 2009 16:15:50 -0500 (EST)
From:	Alan Stern <stern@...land.harvard.edu>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
cc:	pm list <linux-pm@...ts.linux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Arjan van de Ven <arjan@...radead.org>
Subject: Re: [PATCH 1/5] PM: Make the initcall_debug style timing for
 suspend/resume complete

On Mon, 21 Dec 2009, Rafael J. Wysocki wrote:

> From: Rafael J. Wysocki <rjw@...k.pl>
> 
> Commit f2511774863487e61b56a97da07ebf8dd61d7836
> (PM: Add initcall_debug style timing for suspend/resume) introduced
> basic timing instrumentation, needed for a scritps/bootgraph.pl
> equivalent or humans, but it missed the fact that bus types and
> device classes which haven't been switched to using struct dev_pm_ops
> objects yet need special handling.  As a result, the suspend/resume
> timing information is only available for devices whose bus types or
> device classes use struct dev_pm_ops objects, so the majority of
> devices is not covered.
> 
> Fix this by adding basic suspend/resume timing instrumentation for
> devices whose bus types and device classes still don't use struct
> dev_pm_ops objects for power management.  To reduce code duplication
> move the timing code to helper functions.

A minor complaint...

> +/**
>   * device_resume - Execute "resume" callbacks for given device.
>   * @dev: Device to handle.
>   * @state: PM transition of the system being carried out.
> @@ -427,7 +465,7 @@ static int device_resume(struct device *
>  			error = pm_op(dev, dev->bus->pm, state);
>  		} else if (dev->bus->resume) {
>  			pm_dev_dbg(dev, state, "legacy ");
> -			error = dev->bus->resume(dev);
> +			error = legacy_resume(dev, dev->bus->resume);
>  		}
>  		if (error)
>  			goto End;
> @@ -448,7 +486,7 @@ static int device_resume(struct device *
>  			error = pm_op(dev, dev->class->pm, state);
>  		} else if (dev->class->resume) {
>  			pm_dev_dbg(dev, state, "legacy class ");
> -			error = dev->class->resume(dev);
> +			error = legacy_resume(dev, dev->class->resume);
>  		}
>  	}

If none of the method callbacks are non-NULL, this won't print 
anything.  The same is true for device_suspend().

Now maybe you don't _want_ to print anything in that case, but for
debugging purposes it could be useful.

Alan Stern

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