From: James Bottomley <James.Bottomley@xxxxxxxxxxxx>
Date: Mon, 23 Jul 2007 19:50:23 -0500
> On Mon, 2007-07-23 at 23:41 +0100, Mark Fortescue wrote:
> > For targets with a disk connected, I get scan responses of:
> > scsi scan: INQUIRY failed with code 0x8000002
> > after app 170ms.
>
> Thats SCSI status 0x02 (which is CHECK_CONDITION) and driver byte of
> 0x08, which is DRIVER_SENSE (as in the device returned a sense code).
> This is really strange, because the INQUIRY command isn't supposed to be
> allowed to return a sense code for precisely this initial scan reason.
> This tends to point to a device failure.
Devices return CHECK_CONDITION and give SENSE (usually a
UNIT_ATTENTION) when they are given an INQUIRY command too soon after
a scsi bus reset, I saw it all the time when bringing up the new ESP
driver.
There is even special case code in the SCSI bus scan that accepts
certain special cases of UNIT_ATTENTION check conditions as valid:
if (result) {
/*
* not-ready to ready transition [asc/ascq=0x28/0x0]
* or power-on, reset [asc/ascq=0x29/0x0], continue.
* INQUIRY should not yield UNIT_ATTENTION
* but many buggy devices do so anyway.
*/
if ((driver_byte(result) & DRIVER_SENSE) &&
scsi_sense_valid(&sshdr)) {
if ((sshdr.sense_key == UNIT_ATTENTION) &&
((sshdr.asc == 0x28) ||
(sshdr.asc == 0x29)) &&
(sshdr.ascq == 0))
continue;
}
}
asc/ascq values that do not pass this test are what Mark is seeing.
And again this is almost always because the device is being sent
the INQUIRY too soon after a scsi bus reset.
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