[PATCH] bcm43xx: Drain TX status before starting IRQs

Drain the Microcode TX-status-FIFO before we enable IRQs.
This is required, because the FIFO may still have entries left
from a previous run. Those would immediately fire after enabling
IRQs and would lead to an oops in the DMA TXstatus handling code.

Signed-off-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/bcm43xx/bcm43xx_main.c

@@ -1463,6 +1463,23 @@ static void handle_irq_transmit_status(struct bcm43xx_private *bcm)
 	}
 }
 
+static void drain_txstatus_queue(struct bcm43xx_private *bcm)
+{
+	u32 dummy;
+
+	if (bcm->current_core->rev < 5)
+		return;
+	/* Read all entries from the microcode TXstatus FIFO
+	 * and throw them away.
+	 */
+	while (1) {
+		dummy = bcm43xx_read32(bcm, BCM43xx_MMIO_XMITSTAT_0);
+		if (!dummy)
+			break;
+		dummy = bcm43xx_read32(bcm, BCM43xx_MMIO_XMITSTAT_1);
+	}
+}
+
 static void bcm43xx_generate_noise_sample(struct bcm43xx_private *bcm)
 {
 	bcm43xx_shm_write16(bcm, BCM43xx_SHM_SHARED, 0x408, 0x7F7F);
@@ -3532,6 +3549,7 @@ int bcm43xx_select_wireless_core(struct bcm43xx_private *bcm,
 	bcm43xx_macfilter_clear(bcm, BCM43xx_MACFILTER_ASSOC);
 	bcm43xx_macfilter_set(bcm, BCM43xx_MACFILTER_SELF, (u8 *)(bcm->net_dev->dev_addr));
 	bcm43xx_security_init(bcm);
+	drain_txstatus_queue(bcm);
 	ieee80211softmac_start(bcm->net_dev);
 
 	/* Let's go! Be careful after enabling the IRQs.