Message-ID: <431E4A04.5030609@pobox.com>
Date: Tue, 06 Sep 2005 22:01:40 -0400
From: Jeff Garzik <jgarzik@pobox.com>
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To: Brett Russ <russb@emc.com>
CC: linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2.6.13] libata: use common pci remove in ahci
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Brett Russ wrote:
> Jeff Garzik wrote:
>> Brett Russ wrote:
>>> 2) Isn't it wrong for the IRQ disable at the chip to occur *after*
>>> free_irq() is called to disconnect the handler (independent of
>>> question 1...since this is the case currently)?  Granted, all of the
>>> ports have gone through scsi_remove_host() but theoretically there
>>> still is a possibility the chip could interrupt.

Answer:  depends on hardware.

For all hardware, the conditions that generate interrupts should be shut 
down, and then free_irq() is called after that.

Some hardware only needs per-port disable, or nothing besides clearing 
any commands, to ensure that interrupts from that hardware are disabled 
(this excludes shared interrupts, of course).

This logic is another reason why a driver author may choose to implement 
their own PCI ->remove() hook, rather than using the generic 
ata_pci_remove_one().  Eliminates the need for a ->host_stop() hook 
implementation, and allows one to perform tasks before calling 
free_irq(), as well as tasks after the call (normal ->host_stop stuff).

	Jeff


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