Date: Fri, 7 Mar 2008 01:43:01 -0500 From: Jarod Wilson Subject: firewire: fw-sbp2: set single-phase retry_limit Per the SBP-2 specification, all SBP-2 target devices must have a BUSY_TIMEOUT register. Per the 1394-1995 specification, the retry_limt portion of the register should be set to 0x0 initially, and set on the target by a logged in initiator (i.e., a Linux host w/firewire controller(s)). Well, as it turns out, lots of devices these days have actually moved on to starting to implement SBP-3 compliance, which says that retry_limit should default to 0xf instead (yes, SBP-3 stomps directly on 1394-1995, oops). Prior to this change, the firewire driver stack didn't touch retry_limit, and any SBP-3 compliant device worked fine, while SBP-2 compliant ones were unable to retransmit when the host returned an ack_busy_X, which resulted in stalled out I/O, eventually causing the SCSI layer to give up and offline the device. The simple fix is for us to set retry_limit to 0xf in the register for all devices (which actually matches what the old ieee1394 stack did). Prior to this change, a hard disk behind an SBP-2 Prolific PL-3507 bridge chip would routinely encounter buffer I/O errors and wind up offlined by the SCSI layer. With this change, I've encountered zero I/O failures moving tens of GB of data around. Signed-off-by: Jarod Wilson Signed-off-by: Stefan Richter --- drivers/firewire/fw-sbp2.c | 31 +++++++++++++++++++++++++++---- 1 file changed, 27 insertions(+), 4 deletions(-) Index: linux/drivers/firewire/fw-sbp2.c =================================================================== --- linux.orig/drivers/firewire/fw-sbp2.c +++ linux/drivers/firewire/fw-sbp2.c @@ -173,6 +173,7 @@ struct sbp2_target { #define SBP2_ORB_TIMEOUT 2000U /* Timeout in ms */ #define SBP2_ORB_NULL 0x80000000 #define SBP2_MAX_SG_ELEMENT_LENGTH 0xf000 +#define SBP2_RETRY_LIMIT 0xf /* 15 retries */ #define SBP2_DIRECTION_TO_MEDIA 0x0 #define SBP2_DIRECTION_FROM_MEDIA 0x1 @@ -812,6 +813,30 @@ static void sbp2_target_put(struct sbp2_ kref_put(&tgt->kref, sbp2_release_target); } +static void +complete_set_busy_timeout(struct fw_card *card, int rcode, + void *payload, size_t length, void *done) +{ + complete(done); +} + +static void sbp2_set_busy_timeout(struct sbp2_logical_unit *lu) +{ + struct fw_device *device = fw_device(lu->tgt->unit->device.parent); + DECLARE_COMPLETION_ONSTACK(done); + struct fw_transaction t; + static __be32 busy_timeout; + + /* FIXME: we should try to set dual-phase cycle_limit too */ + busy_timeout = cpu_to_be32(SBP2_RETRY_LIMIT); + + fw_send_request(device->card, &t, TCODE_WRITE_QUADLET_REQUEST, + lu->tgt->node_id, lu->generation, device->max_speed, + CSR_REGISTER_BASE + CSR_BUSY_TIMEOUT, &busy_timeout, + sizeof(busy_timeout), complete_set_busy_timeout, &done); + wait_for_completion(&done); +} + static void sbp2_reconnect(struct work_struct *work); static void sbp2_login(struct work_struct *work) @@ -864,10 +889,8 @@ static void sbp2_login(struct work_struc fw_notify("%s: logged in to LUN %04x (%d retries)\n", tgt->bus_id, lu->lun, lu->retries); -#if 0 - /* FIXME: The linux1394 sbp2 does this last step. */ - sbp2_set_busy_timeout(scsi_id); -#endif + /* set appropriate retry limit(s) in BUSY_TIMEOUT register */ + sbp2_set_busy_timeout(lu); PREPARE_DELAYED_WORK(&lu->work, sbp2_reconnect); sbp2_agent_reset(lu);