cxgb3: disable high freq non-data interrupts

Under RX pressure, The HW might generate a high load of interrupts
to signal mac fifo or free lists overflow.
Disable the interrupts, and poll the relevant status bits
to maintain stats.

Signed-off-by: Divy Le Ray <divy@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 86 insertions, 5 deletions

diff --git a/drivers/net/cxgb3/cxgb3_main.c b/drivers/net/cxgb3/cxgb3_main.c
index c32f514c41a..9ff0452fcdd 100644
--- a/drivers/net/cxgb3/cxgb3_main.c
+++ b/drivers/net/cxgb3/cxgb3_main.c
@@ -2471,6 +2471,8 @@ static void t3_adap_check_task(struct work_struct *work)
         struct adapter *adapter = container_of(work, struct adapter,
                                                adap_check_task.work);
         const struct adapter_params *p = &adapter->params;
+        int port;
+        unsigned int v, status, reset;
 
         adapter->check_task_cnt++;
 
@@ -2489,6 +2491,54 @@ static void t3_adap_check_task(struct work_struct *work)
         if (p->rev == T3_REV_B2)
                 check_t3b2_mac(adapter);
 
+        /*
+         * Scan the XGMAC's to check for various conditions which we want to
+         * monitor in a periodic polling manner rather than via an interrupt
+         * condition.  This is used for conditions which would otherwise flood
+         * the system with interrupts and we only really need to know that the
+         * conditions are "happening" ...  For each condition we count the
+         * detection of the condition and reset it for the next polling loop.
+         */
+        for_each_port(adapter, port) {
+                struct cmac *mac =  &adap2pinfo(adapter, port)->mac;
+                u32 cause;
+
+                cause = t3_read_reg(adapter, A_XGM_INT_CAUSE + mac->offset);
+                reset = 0;
+                if (cause & F_RXFIFO_OVERFLOW) {
+                        mac->stats.rx_fifo_ovfl++;
+                        reset |= F_RXFIFO_OVERFLOW;
+                }
+
+                t3_write_reg(adapter, A_XGM_INT_CAUSE + mac->offset, reset);
+        }
+
+        /*
+         * We do the same as above for FL_EMPTY interrupts.
+         */
+        status = t3_read_reg(adapter, A_SG_INT_CAUSE);
+        reset = 0;
+
+        if (status & F_FLEMPTY) {
+                struct sge_qset *qs = &adapter->sge.qs[0];
+                int i = 0;
+
+                reset |= F_FLEMPTY;
+
+                v = (t3_read_reg(adapter, A_SG_RSPQ_FL_STATUS) >> S_FL0EMPTY) &
+                    0xffff;
+
+                while (v) {
+                        qs->fl[i].empty += (v & 1);
+                        if (i)
+                                qs++;
+                        i ^= 1;
+                        v >>= 1;
+                }
+        }
+
+        t3_write_reg(adapter, A_SG_INT_CAUSE, reset);
+
         /* Schedule the next check update if any port is active. */
         spin_lock_irq(&adapter->work_lock);
         if (adapter->open_device_map & PORT_MASK)
diff --git a/drivers/net/cxgb3/regs.h b/drivers/net/cxgb3/regs.h
index a035d5c2444..aa08550ee99 100644
--- a/drivers/net/cxgb3/regs.h
+++ b/drivers/net/cxgb3/regs.h
@@ -170,6 +170,10 @@
 
 #define S_RSPQ0DISABLED    8
 
+#define S_FL0EMPTY    16
+#define V_FL0EMPTY(x) ((x) << S_FL0EMPTY)
+#define F_FL0EMPTY    V_FL0EMPTY(1U)
+
 #define A_SG_EGR_RCQ_DRB_THRSH 0x54
 
 #define S_HIRCQDRBTHRSH    16
@@ -258,6 +262,10 @@
 #define V_RSPQCREDITOVERFOW(x) ((x) << S_RSPQCREDITOVERFOW)
 #define F_RSPQCREDITOVERFOW    V_RSPQCREDITOVERFOW(1U)
 
+#define S_FLEMPTY    1
+#define V_FLEMPTY(x) ((x) << S_FLEMPTY)
+#define F_FLEMPTY    V_FLEMPTY(1U)
+
 #define A_SG_INT_ENABLE 0x60
 
 #define A_SG_CMDQ_CREDIT_TH 0x64
diff --git a/drivers/net/cxgb3/sge.c b/drivers/net/cxgb3/sge.c
index 7d779d18e13..a7555cb3fa4 100644
--- a/drivers/net/cxgb3/sge.c
+++ b/drivers/net/cxgb3/sge.c
@@ -2725,7 +2725,8 @@ irq_handler_t t3_intr_handler(struct adapter *adap, int polling)
  */
 void t3_sge_err_intr_handler(struct adapter *adapter)
 {
-        unsigned int v, status = t3_read_reg(adapter, A_SG_INT_CAUSE);
+        unsigned int v, status = t3_read_reg(adapter, A_SG_INT_CAUSE) &
+                                 ~F_FLEMPTY;
 
         if (status & SGE_PARERR)
                 CH_ALERT(adapter, "SGE parity error (0x%x)\n",
diff --git a/drivers/net/cxgb3/t3_hw.c b/drivers/net/cxgb3/t3_hw.c
index ac2a974dfe3..7c6ee0c9b6f 100644
--- a/drivers/net/cxgb3/t3_hw.c
+++ b/drivers/net/cxgb3/t3_hw.c
@@ -1323,7 +1323,7 @@ static int t3_handle_intr_status(struct adapter *adapter, unsigned int reg,
 #define MC7_INTR_MASK (F_AE | F_UE | F_CE | V_PE(M_PE))
 #define XGM_INTR_MASK (V_TXFIFO_PRTY_ERR(M_TXFIFO_PRTY_ERR) | \
                        V_RXFIFO_PRTY_ERR(M_RXFIFO_PRTY_ERR) | \
-                       F_TXFIFO_UNDERRUN | F_RXFIFO_OVERFLOW)
+                       F_TXFIFO_UNDERRUN)
 #define PCIX_INTR_MASK (F_MSTDETPARERR | F_SIGTARABT | F_RCVTARABT | \
                         F_RCVMSTABT | F_SIGSYSERR | F_DETPARERR | \
                         F_SPLCMPDIS | F_UNXSPLCMP | F_RCVSPLCMPERR | \
@@ -1695,7 +1695,14 @@ static void mc7_intr_handler(struct mc7 *mc7)
 static int mac_intr_handler(struct adapter *adap, unsigned int idx)
 {
         struct cmac *mac = &adap2pinfo(adap, idx)->mac;
-        u32 cause = t3_read_reg(adap, A_XGM_INT_CAUSE + mac->offset);
+        /*
+         * We mask out interrupt causes for which we're not taking interrupts.
+         * This allows us to use polling logic to monitor some of the other
+         * conditions when taking interrupts would impose too much load on the
+         * system.
+         */
+        u32 cause = t3_read_reg(adap, A_XGM_INT_CAUSE + mac->offset) &
+                    ~F_RXFIFO_OVERFLOW;
 
         if (cause & V_TXFIFO_PRTY_ERR(M_TXFIFO_PRTY_ERR)) {
                 mac->stats.tx_fifo_parity_err++;
@@ -3617,7 +3624,15 @@ int t3_prep_adapter(struct adapter *adapter, const struct adapter_info *ai,
         adapter->params.info = ai;
         adapter->params.nports = ai->nports;
         adapter->params.rev = t3_read_reg(adapter, A_PL_REV);
-        adapter->params.linkpoll_period = 0;
+        /*
+         * We used to only run the "adapter check task" once a second if
+         * we had PHYs which didn't support interrupts (we would check
+         * their link status once a second).  Now we check other conditions
+         * in that routine which could potentially impose a very high
+         * interrupt load on the system.  As such, we now always scan the
+         * adapter state once a second ...
+         */
+        adapter->params.linkpoll_period = 10;
         adapter->params.stats_update_period = is_10G(adapter) ?
             MAC_STATS_ACCUM_SECS : (MAC_STATS_ACCUM_SECS * 10);
         adapter->params.pci.vpd_cap_addr =
@@ -3707,7 +3722,14 @@ int t3_prep_adapter(struct adapter *adapter, const struct adapter_info *ai,
                        ETH_ALEN);
                 init_link_config(&p->link_config, p->phy.caps);
                 p->phy.ops->power_down(&p->phy, 1);
-                if (!(p->phy.caps & SUPPORTED_IRQ))
+
+                /*
+                 * If the PHY doesn't support interrupts for link status
+                 * changes, schedule a scan of the adapter links at least
+                 * once a second.
+                 */
+                if (!(p->phy.caps & SUPPORTED_IRQ) &&
+                    adapter->params.linkpoll_period > 10)
                         adapter->params.linkpoll_period = 10;
         }