vxge: MSIX one shot mode

To reduce the possibility of losing an interrupt in the handler due to a
race between an interrupt processing and disable/enable of interrupts,
enable MSIX one shot.

Also, add support for adaptive interrupt coalesing

Signed-off-by: Jon Mason <jon.mason@exar.com>
Signed-off-by: Masroor Vettuparambil <masroor.vettuparambil@exar.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 141 insertions, 18 deletions

diff --git a/drivers/net/vxge/vxge-main.c b/drivers/net/vxge/vxge-main.c
index 0fcac099413a..e40f619b62b1 100644
--- a/drivers/net/vxge/vxge-main.c
+++ b/drivers/net/vxge/vxge-main.c
@@ -371,9 +371,6 @@ vxge_rx_1b_compl(struct __vxge_hw_ring *ringh, void *dtr,
         struct vxge_hw_ring_rxd_info ext_info;
         vxge_debug_entryexit(VXGE_TRACE, "%s: %s:%d",
                 ring->ndev->name, __func__, __LINE__);
-        ring->pkts_processed = 0;
-
-        vxge_hw_ring_replenish(ringh);
 
         do {
                 prefetch((char *)dtr + L1_CACHE_BYTES);
@@ -1588,6 +1585,36 @@ static int vxge_reset_vpath(struct vxgedev *vdev, int vp_id)
         return ret;
 }
 
+/* Configure CI */
+static void vxge_config_ci_for_tti_rti(struct vxgedev *vdev)
+{
+        int i = 0;
+
+        /* Enable CI for RTI */
+        if (vdev->config.intr_type == MSI_X) {
+                for (i = 0; i < vdev->no_of_vpath; i++) {
+                        struct __vxge_hw_ring *hw_ring;
+
+                        hw_ring = vdev->vpaths[i].ring.handle;
+                        vxge_hw_vpath_dynamic_rti_ci_set(hw_ring);
+                }
+        }
+
+        /* Enable CI for TTI */
+        for (i = 0; i < vdev->no_of_vpath; i++) {
+                struct __vxge_hw_fifo *hw_fifo = vdev->vpaths[i].fifo.handle;
+                vxge_hw_vpath_tti_ci_set(hw_fifo);
+                /*
+                 * For Inta (with or without napi), Set CI ON for only one
+                 * vpath. (Have only one free running timer).
+                 */
+                if ((vdev->config.intr_type == INTA) && (i == 0))
+                        break;
+        }
+
+        return;
+}
+
 static int do_vxge_reset(struct vxgedev *vdev, int event)
 {
         enum vxge_hw_status status;
@@ -1753,6 +1780,9 @@ static int do_vxge_reset(struct vxgedev *vdev, int event)
                 netif_tx_wake_all_queues(vdev->ndev);
         }
 
+        /* configure CI */
+        vxge_config_ci_for_tti_rti(vdev);
+
 out:
         vxge_debug_entryexit(VXGE_TRACE,
                 "%s:%d  Exiting...", __func__, __LINE__);
@@ -1793,22 +1823,29 @@ static void vxge_reset(struct work_struct *work)
  */
 static int vxge_poll_msix(struct napi_struct *napi, int budget)
 {
-        struct vxge_ring *ring =
-                container_of(napi, struct vxge_ring, napi);
+        struct vxge_ring *ring = container_of(napi, struct vxge_ring, napi);
+        int pkts_processed;
         int budget_org = budget;
-        ring->budget = budget;
 
+        ring->budget = budget;
+        ring->pkts_processed = 0;
         vxge_hw_vpath_poll_rx(ring->handle);
+        pkts_processed = ring->pkts_processed;
 
         if (ring->pkts_processed < budget_org) {
                 napi_complete(napi);
+
                 /* Re enable the Rx interrupts for the vpath */
                 vxge_hw_channel_msix_unmask(
                                 (struct __vxge_hw_channel *)ring->handle,
                                 ring->rx_vector_no);
+                mmiowb();
         }
 
-        return ring->pkts_processed;
+        /* We are copying and returning the local variable, in case if after
+         * clearing the msix interrupt above, if the interrupt fires right
+         * away which can preempt this NAPI thread */
+        return pkts_processed;
 }
 
 static int vxge_poll_inta(struct napi_struct *napi, int budget)
@@ -1824,6 +1861,7 @@ static int vxge_poll_inta(struct napi_struct *napi, int budget)
         for (i = 0; i < vdev->no_of_vpath; i++) {
                 ring = &vdev->vpaths[i].ring;
                 ring->budget = budget;
+                ring->pkts_processed = 0;
                 vxge_hw_vpath_poll_rx(ring->handle);
                 pkts_processed += ring->pkts_processed;
                 budget -= ring->pkts_processed;
@@ -2054,6 +2092,7 @@ static int vxge_open_vpaths(struct vxgedev *vdev)
                                         netdev_get_tx_queue(vdev->ndev, 0);
                         vpath->fifo.indicate_max_pkts =
                                 vdev->config.fifo_indicate_max_pkts;
+                        vpath->fifo.tx_vector_no = 0;
                         vpath->ring.rx_vector_no = 0;
                         vpath->ring.rx_csum = vdev->rx_csum;
                         vpath->ring.rx_hwts = vdev->rx_hwts;
@@ -2079,6 +2118,61 @@ static int vxge_open_vpaths(struct vxgedev *vdev)
         return VXGE_HW_OK;
 }
 
+/**
+ *  adaptive_coalesce_tx_interrupts - Changes the interrupt coalescing
+ *  if the interrupts are not within a range
+ *  @fifo: pointer to transmit fifo structure
+ *  Description: The function changes boundary timer and restriction timer
+ *  value depends on the traffic
+ *  Return Value: None
+ */
+static void adaptive_coalesce_tx_interrupts(struct vxge_fifo *fifo)
+{
+        fifo->interrupt_count++;
+        if (jiffies > fifo->jiffies + HZ / 100) {
+                struct __vxge_hw_fifo *hw_fifo = fifo->handle;
+
+                fifo->jiffies = jiffies;
+                if (fifo->interrupt_count > VXGE_T1A_MAX_TX_INTERRUPT_COUNT &&
+                    hw_fifo->rtimer != VXGE_TTI_RTIMER_ADAPT_VAL) {
+                        hw_fifo->rtimer = VXGE_TTI_RTIMER_ADAPT_VAL;
+                        vxge_hw_vpath_dynamic_tti_rtimer_set(hw_fifo);
+                } else if (hw_fifo->rtimer != 0) {
+                        hw_fifo->rtimer = 0;
+                        vxge_hw_vpath_dynamic_tti_rtimer_set(hw_fifo);
+                }
+                fifo->interrupt_count = 0;
+        }
+}
+
+/**
+ *  adaptive_coalesce_rx_interrupts - Changes the interrupt coalescing
+ *  if the interrupts are not within a range
+ *  @ring: pointer to receive ring structure
+ *  Description: The function increases of decreases the packet counts within
+ *  the ranges of traffic utilization, if the interrupts due to this ring are
+ *  not within a fixed range.
+ *  Return Value: Nothing
+ */
+static void adaptive_coalesce_rx_interrupts(struct vxge_ring *ring)
+{
+        ring->interrupt_count++;
+        if (jiffies > ring->jiffies + HZ / 100) {
+                struct __vxge_hw_ring *hw_ring = ring->handle;
+
+                ring->jiffies = jiffies;
+                if (ring->interrupt_count > VXGE_T1A_MAX_INTERRUPT_COUNT &&
+                    hw_ring->rtimer != VXGE_RTI_RTIMER_ADAPT_VAL) {
+                        hw_ring->rtimer = VXGE_RTI_RTIMER_ADAPT_VAL;
+                        vxge_hw_vpath_dynamic_rti_rtimer_set(hw_ring);
+                } else if (hw_ring->rtimer != 0) {
+                        hw_ring->rtimer = 0;
+                        vxge_hw_vpath_dynamic_rti_rtimer_set(hw_ring);
+                }
+                ring->interrupt_count = 0;
+        }
+}
+
 /*
  *  vxge_isr_napi
  *  @irq: the irq of the device.
@@ -2139,24 +2233,39 @@ static irqreturn_t vxge_isr_napi(int irq, void *dev_id)
 
 #ifdef CONFIG_PCI_MSI
 
-static irqreturn_t
-vxge_tx_msix_handle(int irq, void *dev_id)
+static irqreturn_t vxge_tx_msix_handle(int irq, void *dev_id)
 {
         struct vxge_fifo *fifo = (struct vxge_fifo *)dev_id;
 
+        adaptive_coalesce_tx_interrupts(fifo);
+
+        vxge_hw_channel_msix_mask((struct __vxge_hw_channel *)fifo->handle,
+                                  fifo->tx_vector_no);
+
+        vxge_hw_channel_msix_clear((struct __vxge_hw_channel *)fifo->handle,
+                                   fifo->tx_vector_no);
+
         VXGE_COMPLETE_VPATH_TX(fifo);
 
+        vxge_hw_channel_msix_unmask((struct __vxge_hw_channel *)fifo->handle,
+                                    fifo->tx_vector_no);
+
+        mmiowb();
+
         return IRQ_HANDLED;
 }
 
-static irqreturn_t
-vxge_rx_msix_napi_handle(int irq, void *dev_id)
+static irqreturn_t vxge_rx_msix_napi_handle(int irq, void *dev_id)
 {
         struct vxge_ring *ring = (struct vxge_ring *)dev_id;
 
-        /* MSIX_IDX for Rx is 1 */
+        adaptive_coalesce_rx_interrupts(ring);
+
         vxge_hw_channel_msix_mask((struct __vxge_hw_channel *)ring->handle,
-                                        ring->rx_vector_no);
+                                  ring->rx_vector_no);
+
+        vxge_hw_channel_msix_clear((struct __vxge_hw_channel *)ring->handle,
+                                   ring->rx_vector_no);
 
         napi_schedule(&ring->napi);
         return IRQ_HANDLED;
@@ -2173,14 +2282,20 @@ vxge_alarm_msix_handle(int irq, void *dev_id)
                 VXGE_HW_VPATH_MSIX_ACTIVE) + VXGE_ALARM_MSIX_ID;
 
         for (i = 0; i < vdev->no_of_vpath; i++) {
+                /* Reduce the chance of loosing alarm interrupts by masking
+                 * the vector. A pending bit will be set if an alarm is
+                 * generated and on unmask the interrupt will be fired.
+                 */
                 vxge_hw_vpath_msix_mask(vdev->vpaths[i].handle, msix_id);
+                vxge_hw_vpath_msix_clear(vdev->vpaths[i].handle, msix_id);
+                mmiowb();
 
                 status = vxge_hw_vpath_alarm_process(vdev->vpaths[i].handle,
                         vdev->exec_mode);
                 if (status == VXGE_HW_OK) {
-
                         vxge_hw_vpath_msix_unmask(vdev->vpaths[i].handle,
-                                        msix_id);
+                                                  msix_id);
+                        mmiowb();
                         continue;
                 }
                 vxge_debug_intr(VXGE_ERR,
@@ -2299,6 +2414,9 @@ static int vxge_enable_msix(struct vxgedev *vdev)
                         vpath->ring.rx_vector_no = (vpath->device_id *
                                                 VXGE_HW_VPATH_MSIX_ACTIVE) + 1;
 
+                        vpath->fifo.tx_vector_no = (vpath->device_id *
+                                                VXGE_HW_VPATH_MSIX_ACTIVE);
+
                         vxge_hw_vpath_msix_set(vpath->handle, tim_msix_id,
                                                VXGE_ALARM_MSIX_ID);
                 }
@@ -2474,8 +2592,9 @@ INTA_MODE:
                         "%s:vxge:INTA", vdev->ndev->name);
                 vxge_hw_device_set_intr_type(vdev->devh,
                         VXGE_HW_INTR_MODE_IRQLINE);
-                vxge_hw_vpath_tti_ci_set(vdev->devh,
-                        vdev->vpaths[0].device_id);
+
+                vxge_hw_vpath_tti_ci_set(vdev->vpaths[0].fifo.handle);
+
                 ret = request_irq((int) vdev->pdev->irq,
                         vxge_isr_napi,
                         IRQF_SHARED, vdev->desc[0], vdev);
@@ -2745,6 +2864,10 @@ static int vxge_open(struct net_device *dev)
         }
 
         netif_tx_start_all_queues(vdev->ndev);
+
+        /* configure CI */
+        vxge_config_ci_for_tti_rti(vdev);
+
         goto out0;
 
 out2:
@@ -3804,7 +3927,7 @@ static void __devinit vxge_device_config_init(
                 break;
 
         case MSI_X:
-                device_config->intr_mode = VXGE_HW_INTR_MODE_MSIX;
+                device_config->intr_mode = VXGE_HW_INTR_MODE_MSIX_ONE_SHOT;
                 break;
         }