On 15.06.2011 [15:02:18 -0500], Brian King wrote:

On 06/15/2011 02:17 PM, Nishanth Aravamudan wrote:

quoted

From what I can tell, the only place that explicitly clears the FROZEN
flag is the error-handling code via ata_eh_thaw_port().

So I thought either we're not invoking the error-handler at probe time
correctly to kick the port or perhaps the SAS code is not clearing the
flag?

I tried the following patch:

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index d51f979..abd0e0b 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c

@@ -3797,6 +3797,7 @@ EXPORT_SYMBOL_GPL(ata_sas_port_alloc);
  */
 int ata_sas_port_start(struct ata_port *ap)
 {
+       ap->pflags &= ~ATA_PFLAG_FROZEN;
        return 0;
 }
 EXPORT_SYMBOL_GPL(ata_sas_port_start);

and the CD-ROM drive works, but I have no idea if it's the right thing
to do. I chose this particular change, FWIW, because we call
ata_sas_port_start before we probe in ata_sas_port_init and it seems
like we need to mark the port as not frozen before we init it? Perhaps
that should really be a call to a thaw function, not sure. Let's just
say the ATA/SAS/SCSI interactions are a bit hard to follow at first :)

That looks like the right thing to do. For ipr's usage of
libata, we don't have the concept of a port frozen state, so this flag
should really never get set. The alternate way to fix this would be to
only set ATA_PFLAG_FROZEN in ata_port_alloc if ap->ops->error_handler
is not NULL.

It seemed like ipr is as you say, but I wasn't sure if it was
appropriate to make the change above in the common libata-scis code or
not. I don't want to break some other device on accident.

Also, I tried your suggestion, but I don't think that can happen in
ata_port_alloc? ata_port_alloc is allocated ap itself, and it seems like
ap->ops typically gets set only after ata_port_alloc returns?

Thanks,
Nish

-- 
Nishanth Aravamudan [off-list ref]
IBM Linux Technology Center