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Subject[PATCH 3/2] Add SATA support to libsas STP piece for SATA on SAS expanders
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This patch adds support for SATA over SAS expanders to the previous two
SATA support in libsas patches.

There were a couple of nasty non trivial things to sort out before this
one could be made to work.

Firstly, I'd like to thank Doug Gilbert for diagnosing a problem with
the LSI expanders where the REPORT_SATA_PHY command was returning the
D2H FIS in the wrong order (Although, here, I think I have to blame the
SAS standards which specifies the FIS "shall be returned in little
endian format" and later on "which means resp[24] shall be FIS type"
The latter, of course, implying big endian format). Just to make sure,
I put a check for the D2H FIS type being in the wrong position and
reverse the FIS data if it is.

The second is a problem outlined in Annex G of the SAS standard (again,
a technical point with D2H FIS ... necessitating a phy reset on certain
conditions).

With the patch, I can now see my SATA-1 disk in a cascaded expander
configuration.

James

---
Index: BUILD-2.6/drivers/scsi/libsas/sas_expander.c
===================================================================
--- BUILD-2.6.orig/drivers/scsi/libsas/sas_expander.c 2006-08-21 21:49:14.000000000 -0500
+++ BUILD-2.6/drivers/scsi/libsas/sas_expander.c 2006-08-22 09:10:40.000000000 -0500
@@ -36,6 +36,8 @@
static int sas_configure_phy(struct domain_device *dev, int phy_id,
u8 *sas_addr, int include);
static int sas_disable_routing(struct domain_device *dev, u8 *sas_addr);
+static int smp_phy_control(struct domain_device *dev, int phy_id,
+ enum phy_func phy_func);

#if 0
/* FIXME: smp needs to migrate into the sas class */
@@ -221,6 +223,36 @@
#define DISCOVER_REQ_SIZE 16
#define DISCOVER_RESP_SIZE 56

+static int sas_ex_phy_discover_helper(struct domain_device *dev, u8 *disc_req,
+ u8 *disc_resp, int single)
+{
+ int i, res;
+
+ disc_req[9] = single;
+ for (i = 1 ; i < 3; i++) {
+ struct discover_resp *dr;
+
+ res = smp_execute_task(dev, disc_req, DISCOVER_REQ_SIZE,
+ disc_resp, DISCOVER_RESP_SIZE);
+ if (res)
+ return res;
+ /* This is detecting a failure to transmit inital
+ * dev to host FIS as described in section G.5 of
+ * sas-2 r 04b */
+ dr = &((struct smp_resp *)disc_resp)->disc;
+ if (!(dr->attached_dev_type == 0 &&
+ dr->attached_sata_dev))
+ break;
+ /* In order to generate the dev to host FIS, we
+ * send a link reset to the expander port */
+ smp_phy_control(dev, single, PHY_FUNC_LINK_RESET);
+ /* Wait for the reset to trigger the negotiation */
+ msleep(500);
+ }
+ sas_set_ex_phy(dev, single, disc_resp);
+ return 0;
+}
+
static int sas_ex_phy_discover(struct domain_device *dev, int single)
{
struct expander_device *ex = &dev->ex_dev;
@@ -241,23 +273,15 @@
disc_req[1] = SMP_DISCOVER;

if (0 <= single && single < ex->num_phys) {
- disc_req[9] = single;
- res = smp_execute_task(dev, disc_req, DISCOVER_REQ_SIZE,
- disc_resp, DISCOVER_RESP_SIZE);
- if (res)
- goto out_err;
- sas_set_ex_phy(dev, single, disc_resp);
+ res = sas_ex_phy_discover_helper(dev, disc_req, disc_resp, single);
} else {
int i;

for (i = 0; i < ex->num_phys; i++) {
- disc_req[9] = i;
- res = smp_execute_task(dev, disc_req,
- DISCOVER_REQ_SIZE, disc_resp,
- DISCOVER_RESP_SIZE);
+ res = sas_ex_phy_discover_helper(dev, disc_req,
+ disc_resp, i);
if (res)
goto out_err;
- sas_set_ex_phy(dev, i, disc_resp);
}
}
out_err:
@@ -492,6 +516,7 @@
{
int res;
u8 *rps_req = alloc_smp_req(RPS_REQ_SIZE);
+ u8 *resp = (u8 *)rps_resp;

if (!rps_req)
return -ENOMEM;
@@ -502,8 +527,28 @@
res = smp_execute_task(dev, rps_req, RPS_REQ_SIZE,
rps_resp, RPS_RESP_SIZE);

+ /* 0x34 is the FIS type for the D2H fis. There's a potential
+ * standards cockup here. sas-2 explicitly specifies the FIS
+ * should be encoded so that FIS type is in resp[24].
+ * However, some expanders endian reverse this. Undo the
+ * reversal here */
+ if (!res && resp[27] == 0x34 && resp[24] != 0x34) {
+ int i;
+
+ for (i = 0; i < 5; i++) {
+ int j = 24 + (i*4);
+ u8 a, b;
+ a = resp[j + 0];
+ b = resp[j + 1];
+ resp[j + 0] = resp[j + 3];
+ resp[j + 1] = resp[j + 2];
+ resp[j + 2] = b;
+ resp[j + 3] = a;
+ }
+ }
+
kfree(rps_req);
- return 0;
+ return res;
}

static void sas_ex_get_linkrate(struct domain_device *parent,
@@ -584,7 +629,19 @@
}
memcpy(child->frame_rcvd, &child->sata_dev.rps_resp.rps.fis,
sizeof(struct dev_to_host_fis));
+
+ rphy = sas_end_device_alloc(phy->port);
+ /* FIXME: error handling */
+ BUG_ON(!rphy);
+
sas_init_dev(child);
+
+ child->rphy = rphy;
+
+ spin_lock(&parent->port->dev_list_lock);
+ list_add_tail(&child->dev_list_node, &parent->port->dev_list);
+ spin_unlock(&parent->port->dev_list_lock);
+
res = sas_discover_sata(child);
if (res) {
SAS_DPRINTK("sas_discover_sata() for device %16llx at "

-
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