Messages in this thread | | | From | Bartlomiej Zolnierkiewicz <> | Subject | Re: Question about IDE disk shutdown | Date | Wed, 2 Jun 2004 00:41:22 +0200 |
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On Tuesday 01 of June 2004 17:13, Tvrtko A. Uršulin wrote: > 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?
You are missing PM code in ide-disk.c. :-)
See idedisk_start_power_step() and idedisk_complete_power_step(), also read comment in <linux/ide.h> about ide_pm_state_*.
Bartlomiej
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