Date: Tue, 13 Mar 2007 15:39:27 -0600 From: Scott Long <scottl@samsco.org> To: Thomas Quinot <thomas@freebsd.org> Cc: josh.carroll@gmail.com, freebsd-scsi@freebsd.org, bug-followup@freebsd.org Subject: Re: kern/103602: drive gets wedged on READ CD CAPACITY if no disc is in Message-ID: <45F71A0F.4080601@samsco.org> In-Reply-To: <20070313205731.GB3866@melamine.cuivre.fr.eu.org> References: <20070313205731.GB3866@melamine.cuivre.fr.eu.org>
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Thomas Quinot wrote: > SCSI guys, > > kern/103602 is a long-standing issue with a Sony DVD drive that has a > strange behaviour (failing to attach and causing an interrupt storm). > > One aspect of this PR was that an ATAPI command timing out was not > correctly reported by the ATAPI/CAM SIM to the XPT layer. This has been > fixed in atapi-cam.c rev. 1.49. > > Now we have a second issue: if there is no disc in the drive, it > times out a READ CD CAPACITY (and any subsequent retry, even if a disc > is then inserted in the drive), instead of returning an appropriate > error (the expected behaviour would be a NOT READY sense key and a > MEDIUM NOT PRESENT ASC). A TEST UNIT READY command seems to behave > properly (reporting the appropriate error if no disc is present, > reporting no error and resetting the drive to a proper state if > one is). > > The timeout causes the unit to fail to attach at boot time if no disc is > present. How should we deal with this situation? One possible option is > to make sure that we first issue a TEST UNIT READY at attach time prior > to issuing READ CD CAPACITY, and not issue the second command if the TUR > returned a NOT READY status. > > The traces below show how the drive behaves in response to TEST UNIT > READY and READ CD CAPACITY in various cases. Complete boot messages are > available in the PR history. > > Thomas. > I'm confused. CAM actually sends a READ_CAPACITY command to the drive, not a READ_CD_CAPACITY command. Are you saying that issuing both a READ_CAPACITY and a READ_CD_CAPACITY to an empty Sony drive results in the same bad behavior? Re-arranging the probe process to issue a TUR first is tricky. I'd rather not do it if possible. Scott
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