Re: [PATCH] PM: add statistics sysfs file for suspend to ram

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Friday, August 05, 2011, Yanmin Zhang wrote:
> On Fri, 2011-08-05 at 09:57 +0800, Liu, ShuoX wrote:
> > > On Thursday, August 04, 2011, Greg KH wrote:
> > > > On Thu, Aug 04, 2011 at 01:13:38PM +0800, Liu, ShuoX wrote:
> > > > > >From a906b0b5b4ff3414ceb9fc7a69a3d7c9d66e46b1 Mon Sep 17
> > > 00:00:00 2001
> > > > > From: ShuoX Liu <shuox.liu@intel.com>
> > > > > Date: Thu, 28 Jul 2011 10:54:22 +0800
> > > > > Subject: [PATCH] PM: add statistics sysfs file for suspend to ram.
> > > >
> > > > What's this stuff here for?  That's not needed (hint, I would have to
> > > > edit it out by hand to be able to apply this patch.)
> > > >
> > > > Thanks for resending a version that passes checkpatch.pl and could be
> > > > applied, but all of my previous comments still stand.  This patch, as
> > > > is, is totally unacceptable.
> > > 
> > > Agreed, plus I'd like to know the motivation behind it.  That is, we have
> > > quite a few debug facilities in that code, so why are they insufficient?
> Thanks Greg, Rafael. We are changing the patch based on your comments.
> 
> > 
> > Some explanation from Yanmin,
> > "We are enabling power features on Medfield. Some testers and developers
> > complain they don't know if system tries suspend-2-ram, and what device 
> > fails to suspend. They need such info for a quick check. If turning on 
> > CONFIG_PM_DEBUG, we get too much info and testers need recompile 
> > the system.
> Comparing with PC/notebook, a mobile enters/exits suspend-2-ram (we call it s3 on
> Medfield) far more frequently. If it can't enter suspend-2-ram in time, the power
> might be used up soon.
> 
> We often find sometimes, a device suspend fails. Then, system retries s3 over
> and over again. As display is off, testers/developers don't know what happens.
> Teh system 
> 
> With the patch, we could know what the bad device is.
> 
> The patch doesn't hurt performance as it's just statistics collector.
> 
> CONFIG_PM_DEBUG is very useful for finer investigation about what happens behind. What
> we provide by the patch is to analyze the issues quickly, even by an ordinary tester.

Well, what about using dynamic debug?

Rafael