1 files changed, 31 insertions, 34 deletions

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 6434e74c04f1..160dc5ad84ae 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -1554,54 +1554,51 @@ static int macb_rx(struct macb_queue *queue, struct napi_struct *napi,
 	return received;
 }
 
+static bool macb_rx_pending(struct macb_queue *queue)
+{
+	struct macb *bp = queue->bp;
+	unsigned int		entry;
+	struct macb_dma_desc	*desc;
+
+	entry = macb_rx_ring_wrap(bp, queue->rx_tail);
+	desc = macb_rx_desc(queue, entry);
+
+	/* Make hw descriptor updates visible to CPU */
+	rmb();
+
+	return (desc->addr & MACB_BIT(RX_USED)) != 0;
+}
+
 static int macb_poll(struct napi_struct *napi, int budget)
 {
 	struct macb_queue *queue = container_of(napi, struct macb_queue, napi);
 	struct macb *bp = queue->bp;
 	int work_done;
-	u32 status;
 
-	status = macb_readl(bp, RSR);
-	macb_writel(bp, RSR, status);
+	work_done = bp->macbgem_ops.mog_rx(queue, napi, budget);
 
-	netdev_vdbg(bp->dev, "poll: status = %08lx, budget = %d\n",
-		    (unsigned long)status, budget);
+	netdev_vdbg(bp->dev, "poll: queue = %u, work_done = %d, budget = %d\n",
+		    (unsigned int)(queue - bp->queues), work_done, budget);
 
-	work_done = bp->macbgem_ops.mog_rx(queue, napi, budget);
-	if (work_done < budget) {
-		napi_complete_done(napi, work_done);
+	if (work_done < budget && napi_complete_done(napi, work_done)) {
+		queue_writel(queue, IER, bp->rx_intr_mask);
 
-		/* RSR bits only seem to propagate to raise interrupts when
-		 * interrupts are enabled at the time, so if bits are already
-		 * set due to packets received while interrupts were disabled,
+		/* Packet completions only seem to propagate to raise
+		 * interrupts when interrupts are enabled at the time, so if
+		 * packets were received while interrupts were disabled,
 		 * they will not cause another interrupt to be generated when
 		 * interrupts are re-enabled.
-		 * Check for this case here. This has been seen to happen
-		 * around 30% of the time under heavy network load.
+		 * Check for this case here to avoid losing a wakeup. This can
+		 * potentially race with the interrupt handler doing the same
+		 * actions if an interrupt is raised just after enabling them,
+		 * but this should be harmless.
 		 */
-		status = macb_readl(bp, RSR);
-		if (status) {
+		if (macb_rx_pending(queue)) {
+			queue_writel(queue, IDR, bp->rx_intr_mask);
 			if (bp->caps & MACB_CAPS_ISR_CLEAR_ON_WRITE)
 				queue_writel(queue, ISR, MACB_BIT(RCOMP));
-			napi_reschedule(napi);
-		} else {
-			queue_writel(queue, IER, bp->rx_intr_mask);
-
-			/* In rare cases, packets could have been received in
-			 * the window between the check above and re-enabling
-			 * interrupts. Therefore, a double-check is required
-			 * to avoid losing a wakeup. This can potentially race
-			 * with the interrupt handler doing the same actions
-			 * if an interrupt is raised just after enabling them,
-			 * but this should be harmless.
-			 */
-			status = macb_readl(bp, RSR);
-			if (unlikely(status)) {
-				queue_writel(queue, IDR, bp->rx_intr_mask);
-				if (bp->caps & MACB_CAPS_ISR_CLEAR_ON_WRITE)
-					queue_writel(queue, ISR, MACB_BIT(RCOMP));
-				napi_schedule(napi);
-			}
+			netdev_vdbg(bp->dev, "poll: packets pending, reschedule\n");
+			napi_schedule(napi);
 		}
 	}