brcm80211: smac: resume transmit fifo upon receiving frames

There have been reports about not being able to use access-points
on channel 12 and 13 or having connectivity issues when these channels
were part of the selected regulatory domain. Upon switching to these
channels the brcmsmac driver suspends the transmit dma fifos. This
patch resumes them upon handing over the first received beacon to
mac80211.

This patch is to be applied to the stable tree for kernel versions
3.2 and 3.3.

Cc: stable@vger.kernel.org
Tested-by: Francesco Saverio Schiavarelli <fschiava@libero.it>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Reviewed-by: Brett Rudley <brudley@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/brcm80211/brcmsmac/main.c

@@ -7614,6 +7614,7 @@ brcms_c_recvctl(struct brcms_c_info *wlc, struct d11rxhdr *rxh,
 {
 	int len_mpdu;
 	struct ieee80211_rx_status rx_status;
+	struct ieee80211_hdr *hdr;
 
 	memset(&rx_status, 0, sizeof(rx_status));
 	prep_mac80211_status(wlc, rxh, p, &rx_status);
@@ -7623,6 +7624,13 @@ brcms_c_recvctl(struct brcms_c_info *wlc, struct d11rxhdr *rxh,
 	skb_pull(p, D11_PHY_HDR_LEN);
 	__skb_trim(p, len_mpdu);
 
+	/* unmute transmit */
+	if (wlc->hw->suspended_fifos) {
+		hdr = (struct ieee80211_hdr *)p->data;
+		if (ieee80211_is_beacon(hdr->frame_control))
+			brcms_b_mute(wlc->hw, false);
+	}
+
 	memcpy(IEEE80211_SKB_RXCB(p), &rx_status, sizeof(rx_status));
 	ieee80211_rx_irqsafe(wlc->pub->ieee_hw, p);
 }