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>

1 files changed, 26 insertions, 4 deletions

diff --git a/drivers/net/cxgb3/t3_hw.c b/drivers/net/cxgb3/t3_hw.c
index ac2a974dfe37..7c6ee0c9b6fc 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;
         }