2 files changed, 12 insertions, 1 deletions

diff --git a/drivers/scsi/isci/host.c b/drivers/scsi/isci/host.c
index 26072f1e9852..2328f98c7f1e 100644
--- a/drivers/scsi/isci/host.c
+++ b/drivers/scsi/isci/host.c
@@ -1091,6 +1091,7 @@ static void isci_host_completion_routine(unsigned long data)
         struct isci_request *request;
         struct isci_request *next_request;
         struct sas_task     *task;
+        u16 active;
 
         INIT_LIST_HEAD(&completed_request_list);
         INIT_LIST_HEAD(&errored_request_list);
@@ -1181,6 +1182,13 @@ static void isci_host_completion_routine(unsigned long data)
                 }
         }
 
+        /* the coalesence timeout doubles at each encoding step, so
+         * update it based on the ilog2 value of the outstanding requests
+         */
+        active = isci_tci_active(ihost);
+        writel(SMU_ICC_GEN_VAL(NUMBER, active) |
+               SMU_ICC_GEN_VAL(TIMER, ISCI_COALESCE_BASE + ilog2(active)),
+               &ihost->smu_registers->interrupt_coalesce_control);
 }
 
 /**
@@ -1471,7 +1479,7 @@ static void sci_controller_ready_state_enter(struct sci_base_state_machine *sm)
         struct isci_host *ihost = container_of(sm, typeof(*ihost), sm);
 
         /* set the default interrupt coalescence number and timeout value. */
-        sci_controller_set_interrupt_coalescence(ihost, 0x10, 250);
+        sci_controller_set_interrupt_coalescence(ihost, 0, 0);
 }
 
 static void sci_controller_ready_state_exit(struct sci_base_state_machine *sm)
diff --git a/drivers/scsi/isci/host.h b/drivers/scsi/isci/host.h
index 062101a39f79..9f33831a2f04 100644
--- a/drivers/scsi/isci/host.h
+++ b/drivers/scsi/isci/host.h
@@ -369,6 +369,9 @@ static inline struct isci_host *dev_to_ihost(struct domain_device *dev)
 #define ISCI_TAG_SEQ(tag) (((tag) >> 12) & (SCI_MAX_SEQ-1))
 #define ISCI_TAG_TCI(tag) ((tag) & (SCI_MAX_IO_REQUESTS-1))
 
+/* interrupt coalescing baseline: 9 == 3 to 5us interrupt delay per command */
+#define ISCI_COALESCE_BASE 9
+
 /* expander attached sata devices require 3 rnc slots */
 static inline int sci_remote_device_node_count(struct isci_remote_device *idev)
 {