libata-sff: Don't scan disabled ports when checking for legacy mode.
libata-sff.c checks for legacy mode by testing if both primary and
secondary ports on a controller are in legacy mode and selects legacy
if either one is. However on some south bridge chips (e.g AMD
SB600/SB700) the secondary port is not wired, and when it is disabled
by setting the disable bit in the PCI header it appears as a fixed
legacy port.
Prevent incorrect detection by not testing ports that are marked as
'dummy'
tj: Addressed Sergei's review points. Other style edits.
Signed-off-by: Darren Stevens <darren@stevens-zone.net>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c
index 4441b5c..2bd92dc 100644
--- a/drivers/ata/libata-sff.c
+++ b/drivers/ata/libata-sff.c
@@ -2428,11 +2428,21 @@ int ata_pci_sff_activate_host(struct ata_host *host,
return rc;
if ((pdev->class >> 8) == PCI_CLASS_STORAGE_IDE) {
- u8 tmp8, mask;
+ u8 tmp8, mask = 0;
- /* TODO: What if one channel is in native mode ... */
+ /*
+ * ATA spec says we should use legacy mode when one
+ * port is in legacy mode, but disabled ports on some
+ * PCI hosts appear as fixed legacy ports, e.g SB600/700
+ * on which the secondary port is not wired, so
+ * ignore ports that are marked as 'dummy' during
+ * this check
+ */
pci_read_config_byte(pdev, PCI_CLASS_PROG, &tmp8);
- mask = (1 << 2) | (1 << 0);
+ if (!ata_port_is_dummy(host->ports[0]))
+ mask |= (1 << 0);
+ if (!ata_port_is_dummy(host->ports[1]))
+ mask |= (1 << 2);
if ((tmp8 & mask) != mask)
legacy_mode = 1;
}