From: "Tvrtko A. =?iso-8859-2?q?Ur=B9ulin?=" <tvrtko.ursulin@zg.htnet.hr>
To: linux-kernel@vger.kernel.org
Subject: Question about IDE disk shutdown
Date: Tue, 1 Jun 2004 17:13:59 +0200
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Hello all,

Probably a trivial question for ones who know it - what IDE commands does 
kernel issue when shutting down (which results in automatic power-off if ACPI 
is enabled)?

According to my hard disk manual, it is absolutely recommended to put the 
drive in STANDBY or SLEEP mode before power cut-off because in that way heads 
are nicely parked. In that way it is guaranteed to have 300000 head 
load/unload cycles minimum, while in other case it is just 20000 cycles.

It also explicitely states that FLUSH CACHE is not to be used for drive 
power-off because it does not park the heads.

Looking at the source I see in ide-disk.c:

	.gen_driver = {
		.shutdown	= ide_device_shutdown,
	},

Following that I see that ide_device_shutdown flushes the cache, and then 
calls dev->bus->suspend(dev, PM_SUSPEND_STANDBY); which is in fact 
generic_ide_suspend, right? There, something called REQ_PM_SUSPEND is issued 
to the drive. As SUSPEND != STANDBY or SLEEP, I am left uncertain.

Is there a place to be worried or I am missing something? 
-
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