scsi: hisi_sas: save delivery queue write pointer

Optimise by saving an avoidable read in the get_free_slot function.  The
delivery queue write pointer will only be updated by software, so don't
bother re-reading what was already written in the previous call to
start_delivery function.

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>

4 files changed, 25 insertions, 8 deletions

diff --git a/drivers/scsi/hisi_sas/hisi_sas.h b/drivers/scsi/hisi_sas/hisi_sas.h
index 9410335caf41..72c98522bd26 100644
--- a/drivers/scsi/hisi_sas/hisi_sas.h
+++ b/drivers/scsi/hisi_sas/hisi_sas.h
@@ -98,6 +98,12 @@ struct hisi_sas_cq {
         int     id;
 };
 
+struct hisi_sas_dq {
+        struct hisi_hba *hisi_hba;
+        int     wr_point;
+        int     id;
+};
+
 struct hisi_sas_device {
         enum sas_device_type    dev_type;
         struct hisi_hba         *hisi_hba;
@@ -194,6 +200,7 @@ struct hisi_hba {
         struct Scsi_Host *shost;
 
         struct hisi_sas_cq cq[HISI_SAS_MAX_QUEUES];
+        struct hisi_sas_dq dq[HISI_SAS_MAX_QUEUES];
         struct hisi_sas_phy phy[HISI_SAS_MAX_PHYS];
         struct hisi_sas_port port[HISI_SAS_MAX_PHYS];
 
diff --git a/drivers/scsi/hisi_sas/hisi_sas_main.c b/drivers/scsi/hisi_sas/hisi_sas_main.c
index 85c73d311e4d..5d5657670d4c 100644
--- a/drivers/scsi/hisi_sas/hisi_sas_main.c
+++ b/drivers/scsi/hisi_sas/hisi_sas_main.c
@@ -1239,11 +1239,16 @@ static int hisi_sas_alloc(struct hisi_hba *hisi_hba, struct Scsi_Host *shost)
 
         for (i = 0; i < hisi_hba->queue_count; i++) {
                 struct hisi_sas_cq *cq = &hisi_hba->cq[i];
+                struct hisi_sas_dq *dq = &hisi_hba->dq[i];
 
                 /* Completion queue structure */
                 cq->id = i;
                 cq->hisi_hba = hisi_hba;
 
+                /* Delivery queue structure */
+                dq->id = i;
+                dq->hisi_hba = hisi_hba;
+
                 /* Delivery queue */
                 s = sizeof(struct hisi_sas_cmd_hdr) * HISI_SAS_QUEUE_SLOTS;
                 hisi_hba->cmd_hdr[i] = dma_alloc_coherent(dev, s,
diff --git a/drivers/scsi/hisi_sas/hisi_sas_v1_hw.c b/drivers/scsi/hisi_sas/hisi_sas_v1_hw.c
index 3b31b2046559..b5374641bdb0 100644
--- a/drivers/scsi/hisi_sas/hisi_sas_v1_hw.c
+++ b/drivers/scsi/hisi_sas/hisi_sas_v1_hw.c
@@ -875,12 +875,13 @@ static int get_wideport_bitmap_v1_hw(struct hisi_hba *hisi_hba, int port_id)
 static int get_free_slot_v1_hw(struct hisi_hba *hisi_hba, int *q, int *s)
 {
         struct device *dev = &hisi_hba->pdev->dev;
+        struct hisi_sas_dq *dq;
         u32 r, w;
         int queue = hisi_hba->queue;
 
         while (1) {
-                w = hisi_sas_read32_relaxed(hisi_hba,
-                                    DLVRY_Q_0_WR_PTR + (queue * 0x14));
+                dq = &hisi_hba->dq[queue];
+                w = dq->wr_point;
                 r = hisi_sas_read32_relaxed(hisi_hba,
                                     DLVRY_Q_0_RD_PTR + (queue * 0x14));
                 if (r == (w+1) % HISI_SAS_QUEUE_SLOTS) {
@@ -903,10 +904,11 @@ static void start_delivery_v1_hw(struct hisi_hba *hisi_hba)
 {
         int dlvry_queue = hisi_hba->slot_prep->dlvry_queue;
         int dlvry_queue_slot = hisi_hba->slot_prep->dlvry_queue_slot;
+        struct hisi_sas_dq *dq = &hisi_hba->dq[dlvry_queue];
 
-        hisi_sas_write32(hisi_hba,
-                         DLVRY_Q_0_WR_PTR + (dlvry_queue * 0x14),
-                         ++dlvry_queue_slot % HISI_SAS_QUEUE_SLOTS);
+        dq->wr_point = ++dlvry_queue_slot % HISI_SAS_QUEUE_SLOTS;
+        hisi_sas_write32(hisi_hba, DLVRY_Q_0_WR_PTR + (dlvry_queue * 0x14),
+                         dq->wr_point);
 }
 
 static int prep_prd_sge_v1_hw(struct hisi_hba *hisi_hba,
diff --git a/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c b/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c
index 11006c99de54..e0c124b6428e 100644
--- a/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c
+++ b/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c
@@ -1023,12 +1023,13 @@ static int get_wideport_bitmap_v2_hw(struct hisi_hba *hisi_hba, int port_id)
 static int get_free_slot_v2_hw(struct hisi_hba *hisi_hba, int *q, int *s)
 {
         struct device *dev = &hisi_hba->pdev->dev;
+        struct hisi_sas_dq *dq;
         u32 r, w;
         int queue = hisi_hba->queue;
 
         while (1) {
-                w = hisi_sas_read32_relaxed(hisi_hba,
-                                            DLVRY_Q_0_WR_PTR + (queue * 0x14));
+                dq = &hisi_hba->dq[queue];
+                w = dq->wr_point;
                 r = hisi_sas_read32_relaxed(hisi_hba,
                                             DLVRY_Q_0_RD_PTR + (queue * 0x14));
                 if (r == (w+1) % HISI_SAS_QUEUE_SLOTS) {
@@ -1051,9 +1052,11 @@ static void start_delivery_v2_hw(struct hisi_hba *hisi_hba)
 {
         int dlvry_queue = hisi_hba->slot_prep->dlvry_queue;
         int dlvry_queue_slot = hisi_hba->slot_prep->dlvry_queue_slot;
+        struct hisi_sas_dq *dq = &hisi_hba->dq[dlvry_queue];
 
+        dq->wr_point = ++dlvry_queue_slot % HISI_SAS_QUEUE_SLOTS;
         hisi_sas_write32(hisi_hba, DLVRY_Q_0_WR_PTR + (dlvry_queue * 0x14),
-                         ++dlvry_queue_slot % HISI_SAS_QUEUE_SLOTS);
+                         dq->wr_point);
 }
 
 static int prep_prd_sge_v2_hw(struct hisi_hba *hisi_hba,