linux-kernel - Re: autosleep suspend too frquent problem

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Message-ID: <20140603120128.GA5080@amd.pavel.ucw.cz>
Date:	Tue, 3 Jun 2014 14:01:28 +0200
From:	Pavel Machek <pavel@....cz>
To:	"Wang, Yalin" <Yalin.Wang@...ymobile.com>
Cc:	"'len.brown@...el.com'" <len.brown@...el.com>,
	"'rjw@...k.pl'" <rjw@...k.pl>,
	"'linux-pm@...r.kernel.org'" <linux-pm@...r.kernel.org>,
	"'linux-kernel@...r.kernel.org'" <linux-kernel@...r.kernel.org>
Subject: Re: autosleep suspend too frquent problem

Hi!


> I found sd card sometimes are damaged/ destroyed 
> On our devices .
> And seems it is caused by kernel's frequently suspend/resume,
> Because during suspend/resume, the driver will suspend/resume sdcard
> Very frequently, this will damaged the sdcard sometimes, and the damage
> is not recoverable ..
> 
> Sometimes kernel will enter suspend and exit suspend very frequently,
> Especially when the system is in idle, but some driver is not idle,
> And it will  wake up the system by irq frequently.
> By our power test result, if system enter suspend /resume very frequently,
> Will consume more power , because it will enable /disable many devices
> During a short time .
> 
> I make a patch to prevent the system to enter suspend/resume state
> More than one time during 2 seconds：

It is good you managed to diagnose the problem, but this si not the
right solution.

Either:

1) don't power down SD card during system suspend

or maybe even better

2) don't power _up_ SD card during system resume. Let it be powered
down until the first access.

Thanks,
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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