firewire: fw-sbp2: Use sbp2 device-provided mgt orb timeout for logins

To be more compliant with section 7.4.8 of the SBP-2 specification,
use the mgt_ORB_timeout specified in the SBP-2 device's config rom
for login ORB attempts (though with some sanity checks). A happy
side-effect is that certain device and controller combinations that
sometimes take more than 20 seconds to get synced up (like my laptop
with just about any SBP-2 device) now function more reliably.

Signed-off-by: Jarod Wilson <jwilson@redhat.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de> (silenced sparse)

1 files changed, 24 insertions, 5 deletions

diff --git a/drivers/firewire/fw-sbp2.c b/drivers/firewire/fw-sbp2.c
index 794badeee0e2..19ece9b6d742 100644
--- a/drivers/firewire/fw-sbp2.c
+++ b/drivers/firewire/fw-sbp2.c
@@ -149,15 +149,17 @@ struct sbp2_target {
 
         unsigned workarounds;
         struct list_head lu_list;
+
+        unsigned int mgt_orb_timeout;
 };
 
 /*
  * Per section 7.4.8 of the SBP-2 spec, a mgt_ORB_timeout value can be
- * provided in the config rom.  A high timeout value really only matters
- * on initial login, where we'll just use 20s rather than hassling with
- * reading the config rom, since it really wouldn't buy us much.
+ * provided in the config rom. Most devices do provide a value, which
+ * we'll use for login management orbs, but with some sane limits.
  */
-#define SBP2_LOGIN_ORB_TIMEOUT          20000   /* Timeout in ms */
+#define SBP2_MIN_LOGIN_ORB_TIMEOUT      5000U   /* Timeout in ms */
+#define SBP2_MAX_LOGIN_ORB_TIMEOUT      40000U  /* Timeout in ms */
 #define SBP2_ORB_TIMEOUT                2000    /* Timeout in ms */
 #define SBP2_ORB_NULL                   0x80000000
 #define SBP2_MAX_SG_ELEMENT_LENGTH      0xf000
@@ -166,6 +168,7 @@ struct sbp2_target {
 #define SBP2_DIRECTION_FROM_MEDIA       0x1
 
 /* Unit directory keys */
+#define SBP2_CSR_UNIT_CHARACTERISTICS   0x3a
 #define SBP2_CSR_FIRMWARE_REVISION      0x3c
 #define SBP2_CSR_LOGICAL_UNIT_NUMBER    0x14
 #define SBP2_CSR_LOGICAL_UNIT_DIRECTORY 0xd4
@@ -527,7 +530,7 @@ sbp2_send_management_orb(struct sbp2_logical_unit *lu, int node_id,
                 orb->request.misc |=
                         MANAGEMENT_ORB_RECONNECT(2) |
                         MANAGEMENT_ORB_EXCLUSIVE(sbp2_param_exclusive_login);
-                timeout = SBP2_LOGIN_ORB_TIMEOUT;
+                timeout = lu->tgt->mgt_orb_timeout;
         } else {
                 timeout = SBP2_ORB_TIMEOUT;
         }
@@ -777,6 +780,7 @@ static int sbp2_scan_unit_dir(struct sbp2_target *tgt, u32 *directory,
 {
         struct fw_csr_iterator ci;
         int key, value;
+        unsigned int timeout;
 
         fw_csr_iterator_init(&ci, directory);
         while (fw_csr_iterator_next(&ci, &key, &value)) {
@@ -799,6 +803,21 @@ static int sbp2_scan_unit_dir(struct sbp2_target *tgt, u32 *directory,
                         *firmware_revision = value;
                         break;
 
+                case SBP2_CSR_UNIT_CHARACTERISTICS:
+                        /* the timeout value is stored in 500ms units */
+                        timeout = ((unsigned int) value >> 8 & 0xff) * 500;
+                        timeout = max(timeout, SBP2_MIN_LOGIN_ORB_TIMEOUT);
+                        tgt->mgt_orb_timeout =
+                                  min(timeout, SBP2_MAX_LOGIN_ORB_TIMEOUT);
+
+                        if (timeout > tgt->mgt_orb_timeout)
+                                fw_notify("%s: config rom contains %ds "
+                                          "management ORB timeout, limiting "
+                                          "to %ds\n", tgt->unit->device.bus_id,
+                                          timeout / 1000,
+                                          tgt->mgt_orb_timeout / 1000);
+                        break;
+
                 case SBP2_CSR_LOGICAL_UNIT_NUMBER:
                         if (sbp2_add_logical_unit(tgt, value) < 0)
                                 return -ENOMEM;