wil6210: reset buff id in status message after completion

Since DR bit and buffer id are written in different dwords of
the status message, the DR bit can already be set to 1 while the
buffer id is not updated yet.
Resetting the buffer id in the status message will allow the driver
to identify such cases and re-read the status message until the buffer
id is written by HW.
In case DR bit is set but buffer id is zero, need to read the status
message again, until a valid id is identified.

In addition to that, move the completed buffer id to the tail of the
free list to prevent its immediate reuse in the upcoming refill.

Signed-off-by: Maya Erez <merez@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

1 files changed, 39 insertions, 11 deletions

diff --git a/drivers/net/wireless/ath/wil6210/txrx_edma.c b/drivers/net/wireless/ath/wil6210/txrx_edma.c
index 492f7bdf39d9..f6fce6ff73d9 100644
--- a/drivers/net/wireless/ath/wil6210/txrx_edma.c
+++ b/drivers/net/wireless/ath/wil6210/txrx_edma.c
@@ -29,6 +29,7 @@
 #define WIL_EDMA_MAX_DATA_OFFSET (2)
 /* RX buffer size must be aligned to 4 bytes */
 #define WIL_EDMA_RX_BUF_LEN_DEFAULT (2048)
+#define MAX_INVALID_BUFF_ID_RETRY (3)
 
 static void wil_tx_desc_unmap_edma(struct device *dev,
 				   union wil_tx_desc *desc,
@@ -312,7 +313,8 @@ static int wil_init_rx_buff_arr(struct wil6210_priv *wil,
 	struct list_head *free = &wil->rx_buff_mgmt.free;
 	int i;
 
-	wil->rx_buff_mgmt.buff_arr = kcalloc(size, sizeof(struct wil_rx_buff),
+	wil->rx_buff_mgmt.buff_arr = kcalloc(size + 1,
+					     sizeof(struct wil_rx_buff),
 					     GFP_KERNEL);
 	if (!wil->rx_buff_mgmt.buff_arr)
 		return -ENOMEM;
@@ -321,14 +323,16 @@ static int wil_init_rx_buff_arr(struct wil6210_priv *wil,
 	INIT_LIST_HEAD(active);
 	INIT_LIST_HEAD(free);
 
-	/* Linkify the list */
+	/* Linkify the list.
+	 * buffer id 0 should not be used (marks invalid id).
+	 */
 	buff_arr = wil->rx_buff_mgmt.buff_arr;
-	for (i = 0; i < size; i++) {
+	for (i = 1; i <= size; i++) {
 		list_add(&buff_arr[i].list, free);
 		buff_arr[i].id = i;
 	}
 
-	wil->rx_buff_mgmt.size = size;
+	wil->rx_buff_mgmt.size = size + 1;
 
 	return 0;
 }
@@ -876,26 +880,50 @@ again:
 
 	/* Extract the buffer ID from the status message */
 	buff_id = le16_to_cpu(wil_rx_status_get_buff_id(msg));
-	if (unlikely(!wil_val_in_range(buff_id, 0, wil->rx_buff_mgmt.size))) {
+
+	while (!buff_id) {
+		struct wil_rx_status_extended *s;
+		int invalid_buff_id_retry = 0;
+
+		wil_dbg_txrx(wil,
+			     "buff_id is not updated yet by HW, (swhead 0x%x)\n",
+			     sring->swhead);
+		if (++invalid_buff_id_retry > MAX_INVALID_BUFF_ID_RETRY)
+			break;
+
+		/* Read the status message again */
+		s = (struct wil_rx_status_extended *)
+			(sring->va + (sring->elem_size * sring->swhead));
+		*(struct wil_rx_status_extended *)msg = *s;
+		buff_id = le16_to_cpu(wil_rx_status_get_buff_id(msg));
+	}
+
+	if (unlikely(!wil_val_in_range(buff_id, 1, wil->rx_buff_mgmt.size))) {
 		wil_err(wil, "Corrupt buff_id=%d, sring->swhead=%d\n",
 			buff_id, sring->swhead);
+		wil_rx_status_reset_buff_id(sring);
 		wil_sring_advance_swhead(sring);
+		sring->invalid_buff_id_cnt++;
 		goto again;
 	}
 
-	wil_sring_advance_swhead(sring);
-
 	/* Extract the SKB from the rx_buff management array */
 	skb = wil->rx_buff_mgmt.buff_arr[buff_id].skb;
 	wil->rx_buff_mgmt.buff_arr[buff_id].skb = NULL;
 	if (!skb) {
 		wil_err(wil, "No Rx skb at buff_id %d\n", buff_id);
+		wil_rx_status_reset_buff_id(sring);
 		/* Move the buffer from the active list to the free list */
-		list_move(&wil->rx_buff_mgmt.buff_arr[buff_id].list,
-			  &wil->rx_buff_mgmt.free);
+		list_move_tail(&wil->rx_buff_mgmt.buff_arr[buff_id].list,
+			       &wil->rx_buff_mgmt.free);
+		wil_sring_advance_swhead(sring);
+		sring->invalid_buff_id_cnt++;
 		goto again;
 	}
 
+	wil_rx_status_reset_buff_id(sring);
+	wil_sring_advance_swhead(sring);
+
 	memcpy(&pa, skb->cb, sizeof(pa));
 	dma_unmap_single(dev, pa, sz, DMA_FROM_DEVICE);
 	dmalen = le16_to_cpu(wil_rx_status_get_length(msg));
@@ -910,8 +938,8 @@ again:
 			  sizeof(struct wil_rx_status_extended), false);
 
 	/* Move the buffer from the active list to the free list */
-	list_move(&wil->rx_buff_mgmt.buff_arr[buff_id].list,
-		  &wil->rx_buff_mgmt.free);
+	list_move_tail(&wil->rx_buff_mgmt.buff_arr[buff_id].list,
+		       &wil->rx_buff_mgmt.free);
 
 	eop = wil_rx_status_get_eop(msg);