[PATCH 1/2] p54: implement multicast filter

[PATCH 1/2] p54: implement multicast filter

[Christian Lamparter]

"For best CPU usage and power consumption, having as few
frames as possible percolate through the stack is
desirable. Hence, the hardware should filter as much
as possible."

Note: Not all firmwares include the multicast filter
feature and the stack does not filter them either.
The ARP filter on the other hand was dropped from the
patch since it does not work correctly:

Quote from: Max Filippov <jcmvbkbc@gmail.com>
<http://www.spinics.net/lists/linux-wireless/msg67466.html>
"In the ARP case, when there's no other traffic on p54spi,
all ARP requests are dropped. But if there's some egress
traffic from p54spi, filter seems to work correctly:
only ARP requests that match filter pass through.

In the multicast case filter seems to work correctly, but
it treats broadcast as subject to that filtering too. By
default only 01:00:5e:00:00:01 gets into priv->mc_maclist,
so we miss all broadcasts.

These two filters seem to interfere:
- if we set ARP filter and multicast filter without bc
	=>  we miss all ARPs if there's no egress traffic;
- if we set ARP filter and multicast filter with bc or
	don't set mc filter at all => we get all ARPs.

This effect does not depend on filter setup order."

Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
---
 drivers/net/wireless/p54/fwio.c |   31 +++++++++++++++++++++++++++++++
 drivers/net/wireless/p54/lmac.h |    1 +
 drivers/net/wireless/p54/main.c |   31 +++++++++++++++++++++++++++++++
 drivers/net/wireless/p54/p54.h  |    2 ++
 4 files changed, 65 insertions(+), 0 deletions(-)

diff --git a/drivers/net/wireless/p54/fwio.c b/drivers/net/wireless/p54/fwio.c
index 2fab7d2..b6a061c 100644
--- a/drivers/net/wireless/p54/fwio.c
+++ b/drivers/net/wireless/p54/fwio.c
@@ -727,3 +727,34 @@ int p54_fetch_statistics(struct p54_common *priv)
 	p54_tx(priv, skb);
 	return 0;
 }
+
+int p54_set_groupfilter(struct p54_common *priv)
+{
+	struct p54_group_address_table *grp;
+	struct sk_buff *skb;
+	bool on = false;
+
+	skb = p54_alloc_skb(priv, P54_HDR_FLAG_CONTROL_OPSET, sizeof(*grp),
+			    P54_CONTROL_TYPE_GROUP_ADDRESS_TABLE, GFP_KERNEL);
+	if (!skb)
+		return -ENOMEM;
+
+	grp = (struct p54_group_address_table *)skb_put(skb, sizeof(*grp));
+
+	on = !(priv->filter_flags & FIF_ALLMULTI) &&
+	     (priv->mc_maclist_num > 0 &&
+	      priv->mc_maclist_num <= MC_FILTER_ADDRESS_NUM);
+
+	if (on) {
+		grp->filter_enable = cpu_to_le16(1);
+		grp->num_address = cpu_to_le16(priv->mc_maclist_num);
+		memcpy(grp->mac_list, priv->mc_maclist, sizeof(grp->mac_list));
+	} else {
+		grp->filter_enable = cpu_to_le16(0);
+		grp->num_address = cpu_to_le16(0);
+		memset(grp->mac_list, 0, sizeof(grp->mac_list));
+	}
+
+	p54_tx(priv, skb);
+	return 0;
+}
diff --git a/drivers/net/wireless/p54/lmac.h b/drivers/net/wireless/p54/lmac.h
index f666482..f9d0dc8 100644
--- a/drivers/net/wireless/p54/lmac.h
+++ b/drivers/net/wireless/p54/lmac.h
@@ -540,6 +540,7 @@ int p54_update_beacon_tim(struct p54_common *priv, u16 aid, bool set);
 int p54_setup_mac(struct p54_common *priv);
 int p54_set_ps(struct p54_common *priv);
 int p54_fetch_statistics(struct p54_common *priv);
+int p54_set_groupfilter(struct p54_common *priv);
 
 /* e/v DCF setup */
 int p54_set_edcf(struct p54_common *priv);
diff --git a/drivers/net/wireless/p54/main.c b/drivers/net/wireless/p54/main.c
index fb26773..03198ed 100644
--- a/drivers/net/wireless/p54/main.c
+++ b/drivers/net/wireless/p54/main.c
@@ -308,6 +308,31 @@ out:
 	return ret;
 }
 
+static u64 p54_prepare_multicast(struct ieee80211_hw *dev,
+				 struct netdev_hw_addr_list *mc_list)
+{
+	struct p54_common *priv = dev->priv;
+	struct netdev_hw_addr *ha;
+	int i;
+
+	BUILD_BUG_ON(ARRAY_SIZE(priv->mc_maclist) !=
+		ARRAY_SIZE(((struct p54_group_address_table *)NULL)->mac_list));
+	/*
+	 * The first entry is reserved for the global broadcast MAC.
+	 * Otherwise the firmware will drop it and ARP will no longer work.
+	 */
+	i = 1;
+	priv->mc_maclist_num = netdev_hw_addr_list_count(mc_list) + i;
+	netdev_hw_addr_list_for_each(ha, mc_list) {
+		memcpy(&priv->mc_maclist[i], ha->addr, ETH_ALEN);
+		i++;
+		if (i >= ARRAY_SIZE(priv->mc_maclist))
+			break;
+	}
+
+	return 1; /* update */
+}
+
 static void p54_configure_filter(struct ieee80211_hw *dev,
 				 unsigned int changed_flags,
 				 unsigned int *total_flags,
@@ -316,12 +341,16 @@ static void p54_configure_filter(struct ieee80211_hw *dev,
 	struct p54_common *priv = dev->priv;
 
 	*total_flags &= FIF_PROMISC_IN_BSS |
+			FIF_ALLMULTI |
 			FIF_OTHER_BSS;
 
 	priv->filter_flags = *total_flags;
 
 	if (changed_flags & (FIF_PROMISC_IN_BSS | FIF_OTHER_BSS))
 		p54_setup_mac(priv);
+
+	if (changed_flags & FIF_ALLMULTI || multicast)
+		p54_set_groupfilter(priv);
 }
 
 static int p54_conf_tx(struct ieee80211_hw *dev, u16 queue,
@@ -591,6 +620,7 @@ static const struct ieee80211_ops p54_ops = {
 	.config			= p54_config,
 	.flush			= p54_flush,
 	.bss_info_changed	= p54_bss_info_changed,
+	.prepare_multicast	= p54_prepare_multicast,
 	.configure_filter	= p54_configure_filter,
 	.conf_tx		= p54_conf_tx,
 	.get_stats		= p54_get_stats,
@@ -660,6 +690,7 @@ struct ieee80211_hw *p54_init_common(size_t priv_data_len)
 	init_completion(&priv->beacon_comp);
 	INIT_DELAYED_WORK(&priv->work, p54_work);
 
+	memset(&priv->mc_maclist[0], ~0, ETH_ALEN);
 	return dev;
 }
 EXPORT_SYMBOL_GPL(p54_init_common);
diff --git a/drivers/net/wireless/p54/p54.h b/drivers/net/wireless/p54/p54.h
index 50730fc..799d05e 100644
--- a/drivers/net/wireless/p54/p54.h
+++ b/drivers/net/wireless/p54/p54.h
@@ -211,8 +211,10 @@ struct p54_common {
 	/* BBP/MAC state */
 	u8 mac_addr[ETH_ALEN];
 	u8 bssid[ETH_ALEN];
+	u8 mc_maclist[4][ETH_ALEN];
 	u16 wakeup_timer;
 	unsigned int filter_flags;
+	int mc_maclist_num;
 	int mode;
 	u32 tsf_low32, tsf_high32;
 	u32 basic_rate_mask;
-- 
1.7.4.4

[PATCH 2/2] carl9170: improve unicast PS buffering

[Christian Lamparter]

Using the ieee80211_sta_block allows the PS code
to handle awake->doze->awake transitions of our
clients in a race-free manner.

Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
---
 drivers/net/wireless/ath/carl9170/carl9170.h |    2 +
 drivers/net/wireless/ath/carl9170/main.c     |   92 +--------------
 drivers/net/wireless/ath/carl9170/tx.c       |  157 +++++++++++++++++---------
 3 files changed, 112 insertions(+), 139 deletions(-)

diff --git a/drivers/net/wireless/ath/carl9170/carl9170.h b/drivers/net/wireless/ath/carl9170/carl9170.h
index b0b3d02..71d6d07 100644
--- a/drivers/net/wireless/ath/carl9170/carl9170.h
+++ b/drivers/net/wireless/ath/carl9170/carl9170.h
@@ -460,6 +460,8 @@ struct carl9170_ba_stats {
 
 struct carl9170_sta_info {
 	bool ht_sta;
+	bool sleeping;
+	atomic_t pending_frames;
 	unsigned int ampdu_max_len;
 	struct carl9170_sta_tid *agg[CARL9170_NUM_TID];
 	struct carl9170_ba_stats stats[CARL9170_NUM_TID];
diff --git a/drivers/net/wireless/ath/carl9170/main.c b/drivers/net/wireless/ath/carl9170/main.c
index c10f132..a357281 100644
--- a/drivers/net/wireless/ath/carl9170/main.c
+++ b/drivers/net/wireless/ath/carl9170/main.c
@@ -1193,6 +1193,8 @@ static int carl9170_op_sta_add(struct ieee80211_hw *hw,
 	struct carl9170_sta_info *sta_info = (void *) sta->drv_priv;
 	unsigned int i;
 
+	atomic_set(&sta_info->pending_frames, 0);
+
 	if (sta->ht_cap.ht_supported) {
 		if (sta->ht_cap.ampdu_density > 6) {
 			/*
@@ -1571,99 +1573,17 @@ static void carl9170_op_sta_notify(struct ieee80211_hw *hw,
 				   enum sta_notify_cmd cmd,
 				   struct ieee80211_sta *sta)
 {
-	struct ar9170 *ar = hw->priv;
 	struct carl9170_sta_info *sta_info = (void *) sta->drv_priv;
-	struct sk_buff *skb, *tmp;
-	struct sk_buff_head free;
-	int i;
 
 	switch (cmd) {
 	case STA_NOTIFY_SLEEP:
-		/*
-		 * Since the peer is no longer listening, we have to return
-		 * as many SKBs as possible back to the mac80211 stack.
-		 * It will deal with the retry procedure, once the peer
-		 * has become available again.
-		 *
-		 * NB: Ideally, the driver should return the all frames in
-		 * the correct, ascending order. However, I think that this
-		 * functionality should be implemented in the stack and not
-		 * here...
-		 */
-
-		__skb_queue_head_init(&free);
-
-		if (sta->ht_cap.ht_supported) {
-			rcu_read_lock();
-			for (i = 0; i < CARL9170_NUM_TID; i++) {
-				struct carl9170_sta_tid *tid_info;
-
-				tid_info = rcu_dereference(sta_info->agg[i]);
-
-				if (!tid_info)
-					continue;
-
-				spin_lock_bh(&ar->tx_ampdu_list_lock);
-				if (tid_info->state >
-				    CARL9170_TID_STATE_SUSPEND)
-					tid_info->state =
-						CARL9170_TID_STATE_SUSPEND;
-				spin_unlock_bh(&ar->tx_ampdu_list_lock);
-
-				spin_lock_bh(&tid_info->lock);
-				while ((skb = __skb_dequeue(&tid_info->queue)))
-					__skb_queue_tail(&free, skb);
-				spin_unlock_bh(&tid_info->lock);
-			}
-			rcu_read_unlock();
-		}
-
-		for (i = 0; i < ar->hw->queues; i++) {
-			spin_lock_bh(&ar->tx_pending[i].lock);
-			skb_queue_walk_safe(&ar->tx_pending[i], skb, tmp) {
-				struct _carl9170_tx_superframe *super;
-				struct ieee80211_hdr *hdr;
-				struct ieee80211_tx_info *info;
-
-				super = (void *) skb->data;
-				hdr = (void *) super->frame_data;
-
-				if (compare_ether_addr(hdr->addr1, sta->addr))
-					continue;
-
-				__skb_unlink(skb, &ar->tx_pending[i]);
-
-				info = IEEE80211_SKB_CB(skb);
-				if (info->flags & IEEE80211_TX_CTL_AMPDU)
-					atomic_dec(&ar->tx_ampdu_upload);
-
-				carl9170_tx_status(ar, skb, false);
-			}
-			spin_unlock_bh(&ar->tx_pending[i].lock);
-		}
-
-		while ((skb = __skb_dequeue(&free)))
-			carl9170_tx_status(ar, skb, false);
-
+		sta_info->sleeping = true;
+		if (atomic_read(&sta_info->pending_frames))
+			ieee80211_sta_block_awake(hw, sta, true);
 		break;
 
 	case STA_NOTIFY_AWAKE:
-		if (!sta->ht_cap.ht_supported)
-			return;
-
-		rcu_read_lock();
-		for (i = 0; i < CARL9170_NUM_TID; i++) {
-			struct carl9170_sta_tid *tid_info;
-
-			tid_info = rcu_dereference(sta_info->agg[i]);
-
-			if (!tid_info)
-				continue;
-
-			if ((tid_info->state == CARL9170_TID_STATE_SUSPEND))
-				tid_info->state = CARL9170_TID_STATE_IDLE;
-		}
-		rcu_read_unlock();
+		sta_info->sleeping = false;
 		break;
 	}
 }
diff --git a/drivers/net/wireless/ath/carl9170/tx.c b/drivers/net/wireless/ath/carl9170/tx.c
index cb70ed7..bee2c92 100644
--- a/drivers/net/wireless/ath/carl9170/tx.c
+++ b/drivers/net/wireless/ath/carl9170/tx.c
@@ -104,6 +104,56 @@ static void carl9170_tx_accounting(struct ar9170 *ar, struct sk_buff *skb)
 	spin_unlock_bh(&ar->tx_stats_lock);
 }
 
+/* needs rcu_read_lock */
+static struct ieee80211_sta *__carl9170_get_tx_sta(struct ar9170 *ar,
+						   struct sk_buff *skb)
+{
+	struct _carl9170_tx_superframe *super = (void *) skb->data;
+	struct ieee80211_hdr *hdr = (void *) super->frame_data;
+	struct ieee80211_vif *vif;
+	unsigned int vif_id;
+
+	vif_id = (super->s.misc & CARL9170_TX_SUPER_MISC_VIF_ID) >>
+		 CARL9170_TX_SUPER_MISC_VIF_ID_S;
+
+	if (WARN_ON_ONCE(vif_id >= AR9170_MAX_VIRTUAL_MAC))
+		return NULL;
+
+	vif = rcu_dereference(ar->vif_priv[vif_id].vif);
+	if (unlikely(!vif))
+		return NULL;
+
+	/*
+	 * Normally we should use wrappers like ieee80211_get_DA to get
+	 * the correct peer ieee80211_sta.
+	 *
+	 * But there is a problem with indirect traffic (broadcasts, or
+	 * data which is designated for other stations) in station mode.
+	 * The frame will be directed to the AP for distribution and not
+	 * to the actual destination.
+	 */
+
+	return ieee80211_find_sta(vif, hdr->addr1);
+}
+
+static void carl9170_tx_ps_unblock(struct ar9170 *ar, struct sk_buff *skb)
+{
+	struct ieee80211_sta *sta;
+	struct carl9170_sta_info *sta_info;
+
+	rcu_read_lock();
+	sta = __carl9170_get_tx_sta(ar, skb);
+	if (unlikely(!sta))
+		goto out_rcu;
+
+	sta_info = (struct carl9170_sta_info *) sta->drv_priv;
+	if (atomic_dec_return(&sta_info->pending_frames) == 0)
+		ieee80211_sta_block_awake(ar->hw, sta, false);
+
+out_rcu:
+	rcu_read_unlock();
+}
+
 static void carl9170_tx_accounting_free(struct ar9170 *ar, struct sk_buff *skb)
 {
 	struct ieee80211_tx_info *txinfo;
@@ -135,6 +185,7 @@ static void carl9170_tx_accounting_free(struct ar9170 *ar, struct sk_buff *skb)
 	}
 
 	spin_unlock_bh(&ar->tx_stats_lock);
+
 	if (atomic_dec_and_test(&ar->tx_total_queued))
 		complete(&ar->tx_flush);
 }
@@ -329,13 +380,10 @@ static void carl9170_tx_status_process_ampdu(struct ar9170 *ar,
 {
 	struct _carl9170_tx_superframe *super = (void *) skb->data;
 	struct ieee80211_hdr *hdr = (void *) super->frame_data;
-	struct ieee80211_tx_info *tx_info;
 	struct carl9170_tx_info *ar_info;
-	struct carl9170_sta_info *sta_info;
 	struct ieee80211_sta *sta;
+	struct carl9170_sta_info *sta_info;
 	struct carl9170_sta_tid *tid_info;
-	struct ieee80211_vif *vif;
-	unsigned int vif_id;
 	u8 tid;
 
 	if (!(txinfo->flags & IEEE80211_TX_CTL_AMPDU) ||
@@ -343,30 +391,10 @@ static void carl9170_tx_status_process_ampdu(struct ar9170 *ar,
 	   (!(super->f.mac_control & cpu_to_le16(AR9170_TX_MAC_AGGR))))
 		return;
 
-	tx_info = IEEE80211_SKB_CB(skb);
-	ar_info = (void *) tx_info->rate_driver_data;
-
-	vif_id = (super->s.misc & CARL9170_TX_SUPER_MISC_VIF_ID) >>
-		 CARL9170_TX_SUPER_MISC_VIF_ID_S;
-
-	if (WARN_ON_ONCE(vif_id >= AR9170_MAX_VIRTUAL_MAC))
-		return;
+	ar_info = (void *) txinfo->rate_driver_data;
 
 	rcu_read_lock();
-	vif = rcu_dereference(ar->vif_priv[vif_id].vif);
-	if (unlikely(!vif))
-		goto out_rcu;
-
-	/*
-	 * Normally we should use wrappers like ieee80211_get_DA to get
-	 * the correct peer ieee80211_sta.
-	 *
-	 * But there is a problem with indirect traffic (broadcasts, or
-	 * data which is designated for other stations) in station mode.
-	 * The frame will be directed to the AP for distribution and not
-	 * to the actual destination.
-	 */
-	sta = ieee80211_find_sta(vif, hdr->addr1);
+	sta = __carl9170_get_tx_sta(ar, skb);
 	if (unlikely(!sta))
 		goto out_rcu;
 
@@ -427,6 +455,7 @@ void carl9170_tx_status(struct ar9170 *ar, struct sk_buff *skb,
 	if (txinfo->flags & IEEE80211_TX_CTL_AMPDU)
 		carl9170_tx_status_process_ampdu(ar, skb, txinfo);
 
+	carl9170_tx_ps_unblock(ar, skb);
 	carl9170_tx_put_skb(skb);
 }
 
@@ -540,11 +569,7 @@ static void carl9170_tx_ampdu_timeout(struct ar9170 *ar)
 	struct sk_buff *skb;
 	struct ieee80211_tx_info *txinfo;
 	struct carl9170_tx_info *arinfo;
-	struct _carl9170_tx_superframe *super;
 	struct ieee80211_sta *sta;
-	struct ieee80211_vif *vif;
-	struct ieee80211_hdr *hdr;
-	unsigned int vif_id;
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(iter, &ar->tx_ampdu_list, list) {
@@ -562,20 +587,7 @@ static void carl9170_tx_ampdu_timeout(struct ar9170 *ar)
 		    msecs_to_jiffies(CARL9170_QUEUE_TIMEOUT)))
 			goto unlock;
 
-		super = (void *) skb->data;
-		hdr = (void *) super->frame_data;
-
-		vif_id = (super->s.misc & CARL9170_TX_SUPER_MISC_VIF_ID) >>
-			 CARL9170_TX_SUPER_MISC_VIF_ID_S;
-
-		if (WARN_ON(vif_id >= AR9170_MAX_VIRTUAL_MAC))
-			goto unlock;
-
-		vif = rcu_dereference(ar->vif_priv[vif_id].vif);
-		if (WARN_ON(!vif))
-			goto unlock;
-
-		sta = ieee80211_find_sta(vif, hdr->addr1);
+		sta = __carl9170_get_tx_sta(ar, skb);
 		if (WARN_ON(!sta))
 			goto unlock;
 
@@ -1199,15 +1211,6 @@ static struct sk_buff *carl9170_tx_pick_skb(struct ar9170 *ar,
 	arinfo = (void *) info->rate_driver_data;
 
 	arinfo->timeout = jiffies;
-
-	/*
-	 * increase ref count to "2".
-	 * Ref counting is the easiest way to solve the race between
-	 * the the urb's completion routine: carl9170_tx_callback and
-	 * wlan tx status functions: carl9170_tx_status/janitor.
-	 */
-	carl9170_tx_get_skb(skb);
-
 	return skb;
 
 err_unlock:
@@ -1228,6 +1231,36 @@ void carl9170_tx_drop(struct ar9170 *ar, struct sk_buff *skb)
 	__carl9170_tx_process_status(ar, super->s.cookie, q);
 }
 
+static bool carl9170_tx_ps_drop(struct ar9170 *ar, struct sk_buff *skb)
+{
+	struct ieee80211_sta *sta;
+	struct carl9170_sta_info *sta_info;
+
+	rcu_read_lock();
+	sta = __carl9170_get_tx_sta(ar, skb);
+	if (!sta)
+		goto out_rcu;
+
+	sta_info = (void *) sta->drv_priv;
+	if (unlikely(sta_info->sleeping)) {
+		struct ieee80211_tx_info *tx_info;
+
+		rcu_read_unlock();
+
+		tx_info = IEEE80211_SKB_CB(skb);
+		if (tx_info->flags & IEEE80211_TX_CTL_AMPDU)
+			atomic_dec(&ar->tx_ampdu_upload);
+
+		tx_info->flags |= IEEE80211_TX_STAT_TX_FILTERED;
+		carl9170_tx_status(ar, skb, false);
+		return true;
+	}
+
+out_rcu:
+	rcu_read_unlock();
+	return false;
+}
+
 static void carl9170_tx(struct ar9170 *ar)
 {
 	struct sk_buff *skb;
@@ -1247,6 +1280,9 @@ static void carl9170_tx(struct ar9170 *ar)
 			if (unlikely(!skb))
 				break;
 
+			if (unlikely(carl9170_tx_ps_drop(ar, skb)))
+				continue;
+
 			atomic_inc(&ar->tx_total_pending);
 
 			q = __carl9170_get_queue(ar, i);
@@ -1256,6 +1292,16 @@ static void carl9170_tx(struct ar9170 *ar)
 			 */
 			skb_queue_tail(&ar->tx_status[q], skb);
 
+			/*
+			 * increase ref count to "2".
+			 * Ref counting is the easiest way to solve the
+			 * race between the urb's completion routine:
+			 *	carl9170_tx_callback
+			 * and wlan tx status functions:
+			 *	carl9170_tx_status/janitor.
+			 */
+			carl9170_tx_get_skb(skb);
+
 			carl9170_usb_tx(ar, skb);
 			schedule_garbagecollector = true;
 		}
@@ -1368,6 +1414,11 @@ void carl9170_op_tx(struct ieee80211_hw *hw, struct sk_buff *skb)
 	 * all ressouces which are associated with the frame.
 	 */
 
+	if (sta) {
+		struct carl9170_sta_info *stai = (void *) sta->drv_priv;
+		atomic_inc(&stai->pending_frames);
+	}
+
 	if (info->flags & IEEE80211_TX_CTL_AMPDU) {
 		run = carl9170_tx_ampdu_queue(ar, sta, skb);
 		if (run)
-- 
1.7.4.4

Re: [PATCH 1/2] p54: implement multicast filter

[Max Filippov]

> "For best CPU usage and power consumption, having as few
> frames as possible percolate through the stack is
> desirable. Hence, the hardware should filter as much
> as possible."
> 
> Note: Not all firmwares include the multicast filter
> feature and the stack does not filter them either.
> The ARP filter on the other hand was dropped from the
> patch since it does not work correctly:
> 
> Quote from: Max Filippov <jcmvbkbc@gmail.com>
> <http://www.spinics.net/lists/linux-wireless/msg67466.html>
> "In the ARP case, when there's no other traffic on p54spi,
> all ARP requests are dropped. But if there's some egress
> traffic from p54spi, filter seems to work correctly:
> only ARP requests that match filter pass through.
> 
> In the multicast case filter seems to work correctly, but
> it treats broadcast as subject to that filtering too. By
> default only 01:00:5e:00:00:01 gets into priv->mc_maclist,
> so we miss all broadcasts.
> 
> These two filters seem to interfere:
> - if we set ARP filter and multicast filter without bc
> 	=>  we miss all ARPs if there's no egress traffic;
> - if we set ARP filter and multicast filter with bc or
> 	don't set mc filter at all => we get all ARPs.
> 
> This effect does not depend on filter setup order."
> 
> Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>

wrt p54spi:

Tested-by: Max Filippov <jcmvbkbc@gmail.com>

Thanks.
-- Max