Messages in this thread | | | Date | Wed, 13 Dec 2006 12:06:44 -0800 | From | "Darrick J. Wong" <> | Subject | Re: [PATCH v2] libata: Simulate REPORT LUNS for ATAPI devices |
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Patrick Mansfield wrote: > On Mon, Dec 04, 2006 at 03:32:20PM -0800, Darrick J. Wong wrote: >> The Quantum GoVault SATAPI removable disk device returns ATA_ERR in >> response to a REPORT LUNS packet. If this happens to an ATAPI device >> that is attached to a SAS controller (this is the case with sas_ata), >> the device does not load because SCSI won't touch a "SCSI device" >> that won't report its LUNs. Since most ATAPI devices don't support >> multiple LUNs anyway, we might as well fake a response like we do for >> ATA devices. > > If the REPORT LUNS fails, we should fall back to a sequential scan. > > Is (or why isn't) the error propagated back to scsi?
I believe the error is reported back to SCSI, which attempts to follow up with TEST UNIT READY. Unfortunately, for some reason the device then gets dropped. libata normally calls __scsi_add_device with lun=0, but SAS calls scsi_scan_target with lun=SCAN_WILD_CARD, which is why SCSI sends REPORT LUNs in the first place.
As an alternative I suppose we could detect ATA devices in sas_rphy_add and change that SCAN_WILD_CARD to "0".
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