Date: Fri, 25 Jan 2008 23:53:54 +0100
From: Ignacy Gawedzki <lkml@qult.net>
To: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Hot (un)plugging of a SATA drive with sata_nv (CK8S) ?
Message-ID: <20080125225354.GA26303@zenon.in.qult.net>
Mail-Followup-To: Ignacy Gawedzki <lkml@qult.net>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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Hi everyone,

I'm having trouble to determine the cause of the following behavior.  I'm not
even sure that I'm supposed to hot plug and unplug a SATA drive from a nForce3
Ultra (apparently CK8S, on a Gigabyte K8NS Ultra 939 mobo) SATA interface, to
begin with.  The information is hard to find given that the sata_nv driver
supports a range of different hardware.

I've recently acquired an external drive with (among others) an eSATA
interface, so I also bought a eSATA->SATA bracket and intend to use that drive
(Lacie d2 quadra 500G) through eSATA.

The thing is that if I boot the machine with the drive plugged and turned on,
it is properly detected and usable.  If, at some point, I want to remove the
drive, I unmount any partitions on it and issue the proper scsiadd -r command
(usually scsiadd -r 1 0 0 0, since this is the second SATA drive) and
everything is fine (I turn the drive off and unplug it), so far.  Next, when
I want to use the drive again, it's still detected alright (although appears
as sdc and not sdb anymore), but the SCSI layer issues "scsi 1:0:0:0:
rejecting I/O to dead device" from time to time.  Then any scsiadd -r 1 0 0 0
command fails with "No such device or address", although it appears in the
output of scsiadd -p or even scsiadd -s (always as 1 0 0 0).  If I ignore that
detail and switch the drive off, then the kernel eventually notices that the
drive is gone and the SCSI layer attempts to stop the device and fails ([sdc]
START_STOP FAILED).  From that moment on, any attempt to plug the drive again
fails.  The kernel issues "ata2: hard resetting port" and "ata2: port is slow
to respond, please be patient (Status 0x80)" periodically, until I switch the
drive off.

If the drive is not present at boot, then hot plugging it fails.  The kernel
first soft resets the port, then issues the "please be patient (Status 0x80)"
message, complains that SRST failed (errno=-16) and goes on hard resetting the
port, issuing "please be patient (Status 0x80)" and complaining that COMRESET
failed (errno=-16), periodically, until the drive is switched off.

If somebody could tell me whether hot-plugging is supposed to work with my
SATA interface, it would be nice. =)  The motherboard happens to offer another
SATA interface (Sil3512A) which is well supported and appears to support
hot-plugging as well, but it conflicts nastily with my PCTV Pro (bttv) card
(which are apparently known to conflict with the Sil SATA interfaces).

Thanks for any help.

Ignacy

-- 
I used to have a sig, but I've stopped smoking now.
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