tg3: Fix firmware event timeouts

The git commit 7c5026aa ("tg3: Add
link state reporting to UMP firmware") introduced code that waits for
previous firmware events to be serviced before attempting to submit a
new event.  Unfortunately that patch contained a bug that cause the
driver to wait 2.5 seconds, rather than 2.5 milliseconds as intended.
This patch fixes that bug.

This bug revealed that not all firmware versions service driver events
though.  Since we do not know which versions of the firmware do and don't
service these events, the driver needs some way to minimize the effects
of the delay.  This patch solves the problem by recording a jiffies
timestamp when it submits an event to the hardware.  If the jiffies
counter shows that 2.5 milliseconds have already passed, a wait is not
needed and the driver can proceed to submit a new event.
Signed-off-by: Matt Carlson <mcarlson@broadcom.com>
Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/tg3.c

@@ -1019,16 +1019,44 @@ static void tg3_mdio_fini(struct tg3 *tp)
 	}
 }
 
+/* tp->lock is held. */
+static inline void tg3_generate_fw_event(struct tg3 *tp)
+{
+	u32 val;
+
+	val = tr32(GRC_RX_CPU_EVENT);
+	val |= GRC_RX_CPU_DRIVER_EVENT;
+	tw32_f(GRC_RX_CPU_EVENT, val);
+
+	tp->last_event_jiffies = jiffies;
+}
+
+#define TG3_FW_EVENT_TIMEOUT_USEC 2500
+
 /* tp->lock is held. */
 static void tg3_wait_for_event_ack(struct tg3 *tp)
 {
 	int i;
+	unsigned int delay_cnt;
+	long time_remain;
+
+	/* If enough time has passed, no wait is necessary. */
+	time_remain = (long)(tp->last_event_jiffies + 1 +
+		      usecs_to_jiffies(TG3_FW_EVENT_TIMEOUT_USEC)) -
+		      (long)jiffies;
+	if (time_remain < 0)
+		return;
+
+	/* Check if we can shorten the wait time. */
+	delay_cnt = jiffies_to_usecs(time_remain);
+	if (delay_cnt > TG3_FW_EVENT_TIMEOUT_USEC)
+		delay_cnt = TG3_FW_EVENT_TIMEOUT_USEC;
+	delay_cnt = (delay_cnt >> 3) + 1;
 
-	/* Wait for up to 2.5 milliseconds */
-	for (i = 0; i < 250000; i++) {
+	for (i = 0; i < delay_cnt; i++) {
 		if (!(tr32(GRC_RX_CPU_EVENT) & GRC_RX_CPU_DRIVER_EVENT))
 			break;
-		udelay(10);
+		udelay(8);
 	}
 }
 
@@ -1077,9 +1105,7 @@ static void tg3_ump_link_report(struct tg3 *tp)
 		val = 0;
 	tg3_write_mem(tp, NIC_SRAM_FW_CMD_DATA_MBOX + 12, val);
 
-	val = tr32(GRC_RX_CPU_EVENT);
-	val |= GRC_RX_CPU_DRIVER_EVENT;
-	tw32_f(GRC_RX_CPU_EVENT, val);
+	tg3_generate_fw_event(tp);
 }
 
 static void tg3_link_report(struct tg3 *tp)
@@ -5953,6 +5979,7 @@ static int tg3_chip_reset(struct tg3 *tp)
 		tg3_read_mem(tp, NIC_SRAM_DATA_CFG, &nic_cfg);
 		if (nic_cfg & NIC_SRAM_DATA_CFG_ASF_ENABLE) {
 			tp->tg3_flags |= TG3_FLAG_ENABLE_ASF;
+			tp->last_event_jiffies = jiffies;
 			if (tp->tg3_flags2 & TG3_FLG2_5750_PLUS)
 				tp->tg3_flags2 |= TG3_FLG2_ASF_NEW_HANDSHAKE;
 		}
@@ -5966,15 +5993,12 @@ static void tg3_stop_fw(struct tg3 *tp)
 {
 	if ((tp->tg3_flags & TG3_FLAG_ENABLE_ASF) &&
 	   !(tp->tg3_flags3 & TG3_FLG3_ENABLE_APE)) {
-		u32 val;
-
 		/* Wait for RX cpu to ACK the previous event. */
 		tg3_wait_for_event_ack(tp);
 
 		tg3_write_mem(tp, NIC_SRAM_FW_CMD_MBOX, FWCMD_NICDRV_PAUSE_FW);
-		val = tr32(GRC_RX_CPU_EVENT);
-		val |= GRC_RX_CPU_DRIVER_EVENT;
-		tw32(GRC_RX_CPU_EVENT, val);
+
+		tg3_generate_fw_event(tp);
 
 		/* Wait for RX cpu to ACK this event. */
 		tg3_wait_for_event_ack(tp);
@@ -7864,8 +7888,6 @@ static void tg3_timer(unsigned long __opaque)
 	if (!--tp->asf_counter) {
 		if ((tp->tg3_flags & TG3_FLAG_ENABLE_ASF) &&
 		    !(tp->tg3_flags3 & TG3_FLG3_ENABLE_APE)) {
-			u32 val;
-
 			tg3_wait_for_event_ack(tp);
 
 			tg3_write_mem(tp, NIC_SRAM_FW_CMD_MBOX,
@@ -7873,9 +7895,8 @@ static void tg3_timer(unsigned long __opaque)
 			tg3_write_mem(tp, NIC_SRAM_FW_CMD_LEN_MBOX, 4);
 			/* 5 seconds timeout */
 			tg3_write_mem(tp, NIC_SRAM_FW_CMD_DATA_MBOX, 5);
-			val = tr32(GRC_RX_CPU_EVENT);
-			val |= GRC_RX_CPU_DRIVER_EVENT;
-			tw32_f(GRC_RX_CPU_EVENT, val);
+
+			tg3_generate_fw_event(tp);
 		}
 		tp->asf_counter = tp->asf_multiplier;
 	}

drivers/net/tg3.h

@@ -2432,7 +2432,10 @@ struct tg3 {
 	struct tg3_ethtool_stats	estats;
 	struct tg3_ethtool_stats	estats_prev;
 
+	union {
 	unsigned long			phy_crc_errors;
+	unsigned long			last_event_jiffies;
+	};
 
 	u32				rx_offset;
 	u32				tg3_flags;