Hi,
I have couple of external drives (Western Digital and Seagate) that
have an eSATA interface. My Linux box with a Marvell HBA (9445) running
Ubuntu 12.04 with 3.2.48 kernel doest not seem to detect the drive. I
tried with the latest upstream kernel and it behaves the same. But both
the drives detect fine if I enter the mvsas BIOS during bootup. So I
have hooked up a SATA analyzer and this is what I found
- When I tried to detect the drives in the mvsas BIOS, all the ATA
commands that the bios issues have the port multiplier byte set to 0.
- If I bootup my Linux system and then connect the drives, the first
IDENTIFY command has the port multiplier set to 0 (this one is
successful) and the subsequent IDENTIFY command has port multiplier set
to 1 (this one fails).
- If I connect any other SATA drives I have to the HBA, all the ATA
commands have port multiplier set to 1 but they detects and work fine.
Just to rule out the port-multiplier possibility I changed the following
line in drivers/scsi/libsas/sas_ata.c - fucntion sas_ata_qc_issue()
ata_tf_to_fis(&qc->tf, 1, 0, (u8*)&task->ata_task.fis);
to
ata_tf_to_fis(&qc->tf, 0, 0, (u8*)&task->ata_task.fis);
now all my drives seem to detect just fine. I believe, the eSATA
interface on these external drives is a port multiplier, which is why
the command fails. Also, the normal drives ignore this field thats why
they work fine with port multiplier being set to either 0 or 1.
Question(s): Are my above assumtions correct? If so, what is the
reasoning behind setting the port multiplier to 1 by default in libsas
layer?
Thanks,
Praveen
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