[PATCH 3.2 011/185] ahci: disabled FBS prior to issuing software reset

Ben Hutchings
2013-12-29T02:51:20Z

From: xiangliang yu <yxlraid@gmail.com>

commit 89dafa20f3daab5b3e0c13d0068a28e8e64e2102 upstream.

Tested with Marvell 88se9125, attached with one port mulitplier(5 ports)
and one disk, we will get following boot log messages if using current
code:

ata8: SATA link up 6.0 Gbps (SStatus 133 SControl 330)
ata8.15: Port Multiplier 1.2, 0x1b4b:0x9715 r160, 5 ports, feat 0x1/0x1f
ahci 0000:03:00.0: FBS is enabled
ata8.00: hard resetting link
ata8.00: SATA link down (SStatus 0 SControl 330)
ata8.01: hard resetting link
ata8.01: SATA link down (SStatus 0 SControl 330)
ata8.02: hard resetting link
ata8.02: SATA link down (SStatus 0 SControl 330)
ata8.03: hard resetting link
ata8.03: SATA link up 6.0 Gbps (SStatus 133 SControl 133)
ata8.04: hard resetting link
ata8.04: failed to resume link (SControl 133)
ata8.04: failed to read SCR 0 (Emask=0x40)
ata8.04: failed to read SCR 0 (Emask=0x40)
ata8.04: failed to read SCR 1 (Emask=0x40)
ata8.04: failed to read SCR 0 (Emask=0x40)
ata8.03: native sectors (2) is smaller than sectors (976773168)
ata8.03: ATA-8: ST3500413AS, JC4B, max UDMA/133
ata8.03: 976773168 sectors, multi 0: LBA48 NCQ (depth 31/32)
ata8.03: configured for UDMA/133
ata8.04: failed to IDENTIFY (I/O error, err_mask=0x100)
ata8.15: hard resetting link
ata8.15: SATA link up 6.0 Gbps (SStatus 133 SControl 330)
ata8.15: Port Multiplier vendor mismatch '0x1b4b' != '0x133'
ata8.15: PMP revalidation failed (errno=-19)
ata8.15: hard resetting link
ata8.15: SATA link up 6.0 Gbps (SStatus 133 SControl 330)
ata8.15: Port Multiplier vendor mismatch '0x1b4b' != '0x133'
ata8.15: PMP revalidation failed (errno=-19)
ata8.15: limiting SATA link speed to 3.0 Gbps
ata8.15: hard resetting link
ata8.15: SATA link up 3.0 Gbps (SStatus 123 SControl 320)
ata8.15: Port Multiplier vendor mismatch '0x1b4b' != '0x133'
ata8.15: PMP revalidation failed (errno=-19)
ata8.15: failed to recover PMP after 5 tries, giving up
ata8.15: Port Multiplier detaching
ata8.03: disabled
ata8.00: disabled
ata8: EH complete

The reason is that current detection code doesn't follow AHCI spec:

First,the port multiplier detection process look like this:

ahci_hardreset(link, class, deadline)
if (class == ATA_DEV_PMP) {
sata_pmp_attach(dev) /* will enable FBS */
sata_pmp_init_links(ap, nr_ports);
ata_for_each_link(link, ap, EDGE) {
sata_std_hardreset(link, class, deadline);
if (link_is_online) /* do soft reset */
ahci_softreset(link, class, deadline);
}
}
But, according to chapter 9.3.9 in AHCI spec: Prior to issuing software
reset, software shall clear PxCMD.ST to '0' and then clear PxFBS.EN to
'0'.

The patch test ok with kernel 3.11.1.

tj: Patch white space contaminated, applied manually with trivial
updates.

Signed-off-by: Xiangliang Yu <yuxiangl@marvell.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/ata/libahci.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)

--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -1247,9 +1247,11 @@ int ahci_do_softreset(struct ata_link *l
{
struct ata_port *ap = link->ap;
struct ahci_host_priv *hpriv = ap->host->private_data;
+ struct ahci_port_priv *pp = ap->private_data;
const char *reason = NULL;
unsigned long now, msecs;
struct ata_taskfile tf;
+ bool fbs_disabled = false;
int rc;

DPRINTK("ENTER\n");
@@ -1259,6 +1261,16 @@ int ahci_do_softreset(struct ata_link *l
if (rc && rc != -EOPNOTSUPP)
ata_link_warn(link, "failed to reset engine (errno=%d)\n", rc);

+ /*
+ * According to AHCI-1.2 9.3.9: if FBS is enable, software shall
+ * clear PxFBS.EN to '0' prior to issuing software reset to devices
+ * that is attached to port multiplier.
+ */
+ if (!ata_is_host_link(link) && pp->fbs_enabled) {
+ ahci_disable_fbs(ap);
+ fbs_disabled = true;
+ }
+
ata_tf_init(link->device, &tf);

/* issue the first D2H Register FIS */
@@ -1299,6 +1311,10 @@ int ahci_do_softreset(struct ata_link *l
} else
*class = ahci_dev_classify(ap);

+ /* re-enable FBS if disabled before */
+ if (fbs_disabled)
+ ahci_enable_fbs(ap);
+
DPRINTK("EXIT, class=%u\n", *class);
return 0;