From: Tejun Heo <tj@kernel.org>
To: Mark Lord <liml@rtr.ca>
Cc: Michael Guntsche <mike@it-loops.com>,
linux-ide@vger.kernel.org, Alan Cox <alan@lxorguk.ukuu.org.uk>,
Jeff Garzik <jeff@garzik.org>
Subject: Re: Fwd: [PATCH #upstream-fixes 1/4] libata: fix device iteration bugs
Date: Tue, 11 Nov 2008 11:45:16 +0900 [thread overview]
Message-ID: <4918F1BC.2070602@kernel.org> (raw)
In-Reply-To: <49184E1A.3010508@rtr.ca>
Mark Lord wrote:
>> On Michael's real old ata_piix, somehow the ERR bit is set on phantom
>> device defeating our phantom device detection logic. We can relax
>> phantom device condition but that increases the risk of misdetection on
>> actual IDENTIFY errors. Any ideas how we can nicely work around this
>> one?
> ..
>
> Mmm.. I'm way out of the loop on this now,
> so please pardon me suggesting things known not to work, but..
>
> 1. Pay attention to ATA status register on this chipset?
> Eg. if it has BUSY, or reads 0x7f, then don't IDENTIFY?
> 2. Check for device signature before trying IDENTIFY?
> 3. Try a r/w test on the data register first, to see if there's
> really hardware attached to it?
We already do 1, 2 and 3. The problem with phantom device is that the
existent device on the channel replies to acesses to the other
non-existent device and the NODEV_HINT detection is the last line of
defense which successfully evades all the other mechanisms. And now
we have this controller/device combination which successfully tricks
it too. :-(
--
tejun
next prev parent reply other threads:[~2008-11-11 2:45 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <6ca8fe89c868f95831328d31c27f9cdb@localhost>
2008-10-27 15:45 ` Fwd: [PATCH #upstream-fixes 1/4] libata: fix device iteration bugs Guntsche Michael
2008-11-10 6:52 ` Tejun Heo
2008-11-10 10:10 ` Michael Guntsche
2008-11-10 10:21 ` Tejun Heo
2008-11-10 15:07 ` Mark Lord
2008-11-11 2:45 ` Tejun Heo [this message]
2008-11-11 4:01 ` Mark Lord
2008-11-11 9:19 ` Sergei Shtylyov
2008-11-11 13:34 ` Michael Guntsche
2008-11-11 14:29 ` Mark Lord
2008-11-11 15:03 ` Guntsche Michael
2008-11-12 1:20 ` Mark Lord
2008-11-12 2:34 ` Tejun Heo
2008-11-12 7:22 ` Michael Guntsche
2008-11-12 8:15 ` Tejun Heo
2008-11-12 9:16 ` Michael Guntsche
2008-11-12 9:27 ` Tejun Heo
2008-11-12 9:43 ` Michael Guntsche
2008-11-12 9:48 ` Tejun Heo
2008-11-12 9:55 ` Michael Guntsche
2008-11-14 2:38 ` Mark Lord
2008-11-14 6:59 ` Michael Guntsche
2008-11-14 17:21 ` Mark Lord
2008-11-14 17:24 ` Mark Lord
2008-11-14 22:26 ` Guntsche Michael
2008-11-15 4:13 ` Mark Lord
2008-11-15 4:17 ` Mark Lord
2008-11-15 9:29 ` Guntsche Michael
2008-11-15 10:22 ` Guntsche Michael
2008-11-15 20:43 ` Mark Lord
2008-11-16 5:14 ` Tejun Heo
2008-11-16 5:49 ` Mark Lord
2008-11-16 8:41 ` Michael Guntsche
2008-11-16 9:15 ` Michael Guntsche
2008-11-16 10:48 ` Sergei Shtylyov
2008-11-16 11:23 ` Alan Cox
2008-11-11 14:27 ` Fwd: " Mark Lord
2008-11-11 14:34 ` Alan Cox
2008-11-12 1:18 ` Mark Lord
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