From: Mark Lord <liml@rtr.ca>
To: Tejun Heo <htejun@gmail.com>
Cc: Jeff Garzik <jgarzik@pobox.com>,
albertcc@tw.ibm.com, linux-ide@vger.kernel.org
Subject: Re: [PATCH libata-dev-2.6:upstream 00/02] atapi: packet task vs. intr race fix
Date: Mon, 22 Aug 2005 10:48:05 -0400 [thread overview]
Message-ID: <4309E5A5.7030604@rtr.ca> (raw)
In-Reply-To: <4308E13E.6070104@gmail.com>
Tejun Heo wrote:
>
> And without interrupt pending bit, shared interrupt means a lot of
> spurious interrupts making it impossible to know when to expect interrupts.
>
> IDE driver deals with this by having only one command active per
> interrupt, but SATA doesn't have such scheme yet. And I don't know if
> such a scheme is desirable at all.
I'm not sure which part of the IDE driver this refers to,
but there is/was code in there from 1994 or so, which enabled
sharing a single IRQ among multiple ISA IDE interfaces using
edge-triggered interrupts (rather than level-triggered).
That particular code did indeed only permit one command active per
interrupt, but only for that situation. But later on, when simplex
DMA host controllers appeared, the scheme got reorganized into
"hardware groups" (hwgroups), which were collections of IDE interfaces
which required mutual exclusion among themselves.
If only the hardware were as simple and as well documented back then
as it is (mostly) today!
Cheers
prev parent reply other threads:[~2005-08-22 21:23 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-08-20 9:17 [PATCH libata-dev-2.6:upstream 00/02] atapi: packet task vs. intr race fix Tejun Heo
2005-08-20 9:17 ` [PATCH libata-dev-2.6:upstream 01/02] atapi: update ata_irq_on Tejun Heo
2005-08-20 9:17 ` [PATCH libata-dev-2.6:upstream 02/02] atapi: fix atapi_packet_task vs. ata_host_intr race Tejun Heo
2005-08-21 19:47 ` [PATCH libata-dev-2.6:upstream 00/02] atapi: packet task vs. intr race fix Jeff Garzik
2005-08-21 20:17 ` Tejun Heo
2005-08-21 20:23 ` Jeff Garzik
2005-08-21 20:40 ` Tejun Heo
2005-08-21 21:24 ` Jeff Garzik
2005-08-21 21:38 ` Tejun Heo
2005-08-21 21:59 ` Jeff Garzik
2005-08-21 23:51 ` Tejun Heo
2005-08-22 0:27 ` Jeff Garzik
2005-08-22 3:57 ` Tejun Heo
2005-08-22 4:01 ` Jeff Garzik
2005-08-22 3:59 ` [PATCH libata:upstream] fix atapi_packet_task vs. intr race Tejun Heo
2005-08-22 4:15 ` Jeff Garzik
2005-08-22 5:59 ` [PATCH libata:upstream] fix atapi_packet_task vs. intr race (take 2) Tejun Heo
2005-08-22 6:54 ` Jeff Garzik
2005-08-22 7:06 ` Tejun Heo
2005-08-23 5:06 ` Jeff Garzik
2005-08-21 20:25 ` [PATCH libata-dev-2.6:upstream 00/02] atapi: packet task vs. intr race fix Jeff Garzik
2005-08-22 14:48 ` Mark Lord [this message]
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