Date: Tue, 7 Mar 2000 06:09:09 -0800 (PST) From: Matthew Jacob <mjacob@feral.com> To: Nick Hibma <n_hibma@calcaphon.com> Cc: FreeBSD SCSI Mailing List <scsi@FreeBSD.ORG> Subject: Re: first INQUIRY goes round in circles (fwd) Message-ID: <Pine.BSF.4.10.10003070601300.26781-100000@beppo.feral.com> In-Reply-To: <Pine.BSF.4.20.0003071017001.1042-100000@localhost>
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> What I don't understand is why the drive does not clear the Unit > Attention after REQUEST SENSE has been sent. Uh, f/w bug? > > The solution to all this Jim pointed out was to not request sense after > INQUIRY. This I can live with as it is a valid solution. If INQUIRY > fails, the data stage of the USB transfer will fail and you have another > indicator that things went wrong. Note that might be a case in which it's possible for an unadorned INQUIRY* to generate a CHECK CONDITION- that's when there's a parity error on the IDENTIFY message at the start of the command or a parity error sending the CDB. I haven't done this level of SCSI for 10 years and don't have the spec in front of me, but IIRC it's up to the target as to how it decides it wants to cope with received bytes with parity errors so the mechanisms that cope with parity errors while the command is active may not be used and a CHECK CONDITION with the ASC/ASCQ may be latched up. -matt *The second INQUIRY that FreeBSD's xpt_probe always sends that asks for the VPD info will generally always get a CHECK CONDITION for devices that don't support VDP info, so blindly saying "don't request sense after an INQUIRY" is a Bad Thing To Do (tm) as it will leave the latched up Illegal Bit in CDB for the next command to have to cope with- which will be the poor old Test Unit Ready. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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