scsi: hisi_sas: save completion queue read pointer

Optimise by saving an avoidable read in the cq interrupt.  The queue
read pointer will only be updated by software, so don't bother
re-reading what was already written in the previous interrupt.

Signed-off-by: John Garry <john.garry@huawei.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

3 files changed, 5 insertions, 7 deletions

diff --git a/drivers/scsi/hisi_sas/hisi_sas.h b/drivers/scsi/hisi_sas/hisi_sas.h
index ca55ec2974e0..9410335caf41 100644
--- a/drivers/scsi/hisi_sas/hisi_sas.h
+++ b/drivers/scsi/hisi_sas/hisi_sas.h
@@ -94,6 +94,7 @@ struct hisi_sas_port {
 
 struct hisi_sas_cq {
         struct hisi_hba *hisi_hba;
+        int     rd_point;
         int     id;
 };
 
diff --git a/drivers/scsi/hisi_sas/hisi_sas_v1_hw.c b/drivers/scsi/hisi_sas/hisi_sas_v1_hw.c
index 1abbc2e162df..3b31b2046559 100644
--- a/drivers/scsi/hisi_sas/hisi_sas_v1_hw.c
+++ b/drivers/scsi/hisi_sas/hisi_sas_v1_hw.c
@@ -1565,14 +1565,11 @@ static irqreturn_t cq_interrupt_v1_hw(int irq, void *p)
         struct hisi_sas_complete_v1_hdr *complete_queue =
                         (struct hisi_sas_complete_v1_hdr *)
                         hisi_hba->complete_hdr[queue];
-        u32 irq_value, rd_point, wr_point;
+        u32 irq_value, rd_point = cq->rd_point, wr_point;
 
         irq_value = hisi_sas_read32(hisi_hba, OQ_INT_SRC);
 
         hisi_sas_write32(hisi_hba, OQ_INT_SRC, 1 << queue);
-
-        rd_point = hisi_sas_read32(hisi_hba,
-                        COMPL_Q_0_RD_PTR + (0x14 * queue));
         wr_point = hisi_sas_read32(hisi_hba,
                         COMPL_Q_0_WR_PTR + (0x14 * queue));
 
@@ -1600,6 +1597,7 @@ static irqreturn_t cq_interrupt_v1_hw(int irq, void *p)
         }
 
         /* update rd_point */
+        cq->rd_point = rd_point;
         hisi_sas_write32(hisi_hba, COMPL_Q_0_RD_PTR + (0x14 * queue), rd_point);
 
         return IRQ_HANDLED;
diff --git a/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c b/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c
index bf9b693a717f..11006c99de54 100644
--- a/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c
+++ b/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c
@@ -2049,7 +2049,7 @@ static irqreturn_t cq_interrupt_v2_hw(int irq_no, void *p)
         struct hisi_sas_slot *slot;
         struct hisi_sas_itct *itct;
         struct hisi_sas_complete_v2_hdr *complete_queue;
-        u32 irq_value, rd_point, wr_point, dev_id;
+        u32 irq_value, rd_point = cq->rd_point, wr_point, dev_id;
         int queue = cq->id;
 
         complete_queue = hisi_hba->complete_hdr[queue];
@@ -2057,8 +2057,6 @@ static irqreturn_t cq_interrupt_v2_hw(int irq_no, void *p)
 
         hisi_sas_write32(hisi_hba, OQ_INT_SRC, 1 << queue);
 
-        rd_point = hisi_sas_read32(hisi_hba, COMPL_Q_0_RD_PTR +
-                                   (0x14 * queue));
         wr_point = hisi_sas_read32(hisi_hba, COMPL_Q_0_WR_PTR +
                                    (0x14 * queue));
 
@@ -2106,6 +2104,7 @@ static irqreturn_t cq_interrupt_v2_hw(int irq_no, void *p)
         }
 
         /* update rd_point */
+        cq->rd_point = rd_point;
         hisi_sas_write32(hisi_hba, COMPL_Q_0_RD_PTR + (0x14 * queue), rd_point);
         return IRQ_HANDLED;
 }