From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Jason Keltz <jas@cse.yorku.ca>
Cc: jgarzik@pobox.com, linux-ide@vger.kernel.org
Subject: Re: ide cdrom problems on new imac
Date: Fri, 6 Jun 2008 21:49:47 +0100 [thread overview]
Message-ID: <20080606214947.06e19074@core> (raw)
In-Reply-To: <484970DC.3060209@cse.yorku.ca>
> It isn't clear to me whether the device is recognized by libata
> ata_piix, or just by a separate kernel IDE Intel PIIX driver?
One slot by each - CD by old IDE disk by libata in the dump you gave
> [<c025d0ae>] (ide_intr+0x0/0x11e)
> Disabling IRQ #185
and old IDE broke
No kernel that old supports the needed workarounds for the ICH behaviour
change. Intel changed the ICH behaviour on IRQ handling in the later
chips in some configurations that are mostly used on the mac.
The SATA backport in Centos 4.x doesn't include the needed changes nor
does the IDE layer. Ditto I believe 5.x.
You need to use the current IRQ clearing logic for both drivers - the old
logic only clears the ata status register on PIO events, the newer one
clears both the ata and DMA status to work around the Intel funny.
[By a strict reading of the spec the Intel behaviour does appear allowed,
although I hope Intel didn't intend it ...]
Alan
next prev parent reply other threads:[~2008-06-06 21:06 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-06-06 17:16 ide cdrom problems on new imac Jason Keltz
2008-06-06 20:49 ` Alan Cox [this message]
2008-06-07 1:48 ` Jason Keltz
2008-06-07 10:01 ` Alan Cox
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