wil6210: Add proper handling for invalid frames on Rx

On Rx, when invalid frame is received and dropped,
reaping of next frames from Rx ring is stopped.

This stops NAPI polling and re-enables the Rx interrupt.

However, in cases where no more frames received,
interrupt will not be triggered and rest of Rx frames
will not be processed.

Skip bad frames and continue to reap Rx packets when
such frames are encountered, and add statistics for
such frames for debug.

Signed-off-by: Hamad Kadmany <qca_hkadmany@qca.qualcomm.com>
Signed-off-by: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

drivers/net/wireless/ath/wil6210/txrx.c

@@ -379,14 +379,16 @@ static struct sk_buff *wil_vring_reap_rx(struct wil6210_priv *wil,
 	u16 dmalen;
 	u8 ftype;
 	int cid;
-	int i = (int)vring->swhead;
+	int i;
 	struct wil_net_stats *stats;
 
 	BUILD_BUG_ON(sizeof(struct vring_rx_desc) > sizeof(skb->cb));
 
+again:
 	if (unlikely(wil_vring_is_empty(vring)))
 		return NULL;
 
+	i = (int)vring->swhead;
 	_d = &vring->va[i].rx;
 	if (unlikely(!(_d->dma.status & RX_DMA_STATUS_DU))) {
 		/* it is not error, we just reached end of Rx done area */
@@ -398,7 +400,7 @@ static struct sk_buff *wil_vring_reap_rx(struct wil6210_priv *wil,
 	wil_vring_advance_head(vring, 1);
 	if (!skb) {
 		wil_err(wil, "No Rx skb at [%d]\n", i);
-		return NULL;
+		goto again;
 	}
 	d = wil_skb_rxdesc(skb);
 	*d = *_d;
@@ -412,10 +414,14 @@ static struct sk_buff *wil_vring_reap_rx(struct wil6210_priv *wil,
 	wil_hex_dump_txrx("Rx ", DUMP_PREFIX_NONE, 32, 4,
 			  (const void *)d, sizeof(*d), false);
 
+	cid = wil_rxdesc_cid(d);
+	stats = &wil->sta[cid].stats;
+
 	if (unlikely(dmalen > sz)) {
 		wil_err(wil, "Rx size too large: %d bytes!\n", dmalen);
+		stats->rx_large_frame++;
 		kfree_skb(skb);
-		return NULL;
+		goto again;
 	}
 	skb_trim(skb, dmalen);
 
@@ -424,8 +430,6 @@ static struct sk_buff *wil_vring_reap_rx(struct wil6210_priv *wil,
 	wil_hex_dump_txrx("Rx ", DUMP_PREFIX_OFFSET, 16, 1,
 			  skb->data, skb_headlen(skb), false);
 
-	cid = wil_rxdesc_cid(d);
-	stats = &wil->sta[cid].stats;
 	stats->last_mcs_rx = wil_rxdesc_mcs(d);
 	if (stats->last_mcs_rx < ARRAY_SIZE(stats->rx_per_mcs))
 		stats->rx_per_mcs[stats->last_mcs_rx]++;
@@ -446,15 +450,17 @@ static struct sk_buff *wil_vring_reap_rx(struct wil6210_priv *wil,
 	if (unlikely(ftype != IEEE80211_FTYPE_DATA)) {
 		wil_dbg_txrx(wil, "Non-data frame ftype 0x%08x\n", ftype);
 		/* TODO: process it */
+		stats->rx_non_data_frame++;
 		kfree_skb(skb);
-		return NULL;
+		goto again;
 	}
 
 	if (unlikely(skb->len < ETH_HLEN + snaplen)) {
 		wil_err(wil, "Short frame, len = %d\n", skb->len);
 		/* TODO: process it (i.e. BAR) */
+		stats->rx_short_frame++;
 		kfree_skb(skb);
-		return NULL;
+		goto again;
 	}
 
 	/* L4 IDENT is on when HW calculated checksum, check status