iwlwifi: do not schedule tasklet when rcv unused irq

The nic controller's scheduler interrupt (CSR_INT_BIT_SCD) indicates
to the driver that scheduler finished to transmit the frame/frames.
This bit is not used and the tasklet should thus not be scheduled upon
its receipt.

Signed-off-by: Joonwoo Park <joonwpark81@gmail.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/wireless/iwlwifi/iwl-3945-hw.h

@@ -373,7 +373,7 @@ struct iwl3945_eeprom {
 #define CSR_INT_BIT_HW_ERR       (1 << 29) /* DMA hardware error FH_INT[31] */
 #define CSR_INT_BIT_DNLD         (1 << 28) /* uCode Download */
 #define CSR_INT_BIT_FH_TX        (1 << 27) /* Tx DMA FH_INT[1:0] */
-#define CSR_INT_BIT_MAC_CLK_ACTV (1 << 26) /* NIC controller's clock toggled on/off */
+#define CSR_INT_BIT_SCD          (1 << 26) /* TXQ pointer advanced */
 #define CSR_INT_BIT_SW_ERR       (1 << 25) /* uCode error */
 #define CSR_INT_BIT_RF_KILL      (1 << 7)  /* HW RFKILL switch GP_CNTRL[27] toggled */
 #define CSR_INT_BIT_CT_KILL      (1 << 6)  /* Critical temp (chip too hot) rfkill */

drivers/net/wireless/iwlwifi/iwl-4965-hw.h

@@ -465,7 +465,7 @@ struct iwl4965_eeprom {
 #define CSR_INT_BIT_HW_ERR       (1 << 29) /* DMA hardware error FH_INT[31] */
 #define CSR_INT_BIT_DNLD         (1 << 28) /* uCode Download */
 #define CSR_INT_BIT_FH_TX        (1 << 27) /* Tx DMA FH_INT[1:0] */
-#define CSR_INT_BIT_MAC_CLK_ACTV (1 << 26) /* NIC controller's clock toggled on/off */
+#define CSR_INT_BIT_SCD          (1 << 26) /* TXQ pointer advanced */
 #define CSR_INT_BIT_SW_ERR       (1 << 25) /* uCode error */
 #define CSR_INT_BIT_RF_KILL      (1 << 7)  /* HW RFKILL switch GP_CNTRL[27] toggled */
 #define CSR_INT_BIT_CT_KILL      (1 << 6)  /* Critical temp (chip too hot) rfkill */

drivers/net/wireless/iwlwifi/iwl3945-base.c

@@ -4759,8 +4759,9 @@ static void iwl3945_irq_tasklet(struct iwl3945_priv *priv)
 #ifdef CONFIG_IWL3945_DEBUG
 	if (iwl3945_debug_level & (IWL_DL_ISR)) {
 		/* NIC fires this, but we don't use it, redundant with WAKEUP */
-		if (inta & CSR_INT_BIT_MAC_CLK_ACTV)
-			IWL_DEBUG_ISR("Microcode started or stopped.\n");
+		if (inta & CSR_INT_BIT_SCD)
+			IWL_DEBUG_ISR("Scheduler finished to transmit "
+				      "the frame/frames.\n");
 
 		/* Alive notification via Rx interrupt will do the real work */
 		if (inta & CSR_INT_BIT_ALIVE)
@@ -4768,7 +4769,7 @@ static void iwl3945_irq_tasklet(struct iwl3945_priv *priv)
 	}
 #endif
 	/* Safely ignore these bits for debug checks below */
-	inta &= ~(CSR_INT_BIT_MAC_CLK_ACTV | CSR_INT_BIT_ALIVE);
+	inta &= ~(CSR_INT_BIT_SCD | CSR_INT_BIT_ALIVE);
 
 	/* HW RF KILL switch toggled (4965 only) */
 	if (inta & CSR_INT_BIT_RF_KILL) {
@@ -4904,8 +4905,11 @@ static irqreturn_t iwl3945_isr(int irq, void *data)
 	IWL_DEBUG_ISR("ISR inta 0x%08x, enabled 0x%08x, fh 0x%08x\n",
 		      inta, inta_mask, inta_fh);
 
+	inta &= ~CSR_INT_BIT_SCD;
+
 	/* iwl3945_irq_tasklet() will service interrupts and re-enable them */
-	tasklet_schedule(&priv->irq_tasklet);
+	if (likely(inta || inta_fh))
+		tasklet_schedule(&priv->irq_tasklet);
 unplugged:
 	spin_unlock(&priv->lock);
 

drivers/net/wireless/iwlwifi/iwl4965-base.c

@@ -5137,8 +5137,9 @@ static void iwl4965_irq_tasklet(struct iwl4965_priv *priv)
 #ifdef CONFIG_IWL4965_DEBUG
 	if (iwl4965_debug_level & (IWL_DL_ISR)) {
 		/* NIC fires this, but we don't use it, redundant with WAKEUP */
-		if (inta & CSR_INT_BIT_MAC_CLK_ACTV)
-			IWL_DEBUG_ISR("Microcode started or stopped.\n");
+		if (inta & CSR_INT_BIT_SCD)
+			IWL_DEBUG_ISR("Scheduler finished to transmit "
+				      "the frame/frames.\n");
 
 		/* Alive notification via Rx interrupt will do the real work */
 		if (inta & CSR_INT_BIT_ALIVE)
@@ -5146,7 +5147,7 @@ static void iwl4965_irq_tasklet(struct iwl4965_priv *priv)
 	}
 #endif
 	/* Safely ignore these bits for debug checks below */
-	inta &= ~(CSR_INT_BIT_MAC_CLK_ACTV | CSR_INT_BIT_ALIVE);
+	inta &= ~(CSR_INT_BIT_SCD | CSR_INT_BIT_ALIVE);
 
 	/* HW RF KILL switch toggled */
 	if (inta & CSR_INT_BIT_RF_KILL) {
@@ -5275,8 +5276,11 @@ static irqreturn_t iwl4965_isr(int irq, void *data)
 	IWL_DEBUG_ISR("ISR inta 0x%08x, enabled 0x%08x, fh 0x%08x\n",
 		      inta, inta_mask, inta_fh);
 
+	inta &= ~CSR_INT_BIT_SCD;
+
 	/* iwl4965_irq_tasklet() will service interrupts and re-enable them */
-	tasklet_schedule(&priv->irq_tasklet);
+	if (likely(inta || inta_fh))
+		tasklet_schedule(&priv->irq_tasklet);
 
  unplugged:
 	spin_unlock(&priv->lock);