net: macb: Apply RXUBR workaround only to versions with errata

The interrupt handler contains a workaround for RX hang applicable
to Zynq and AT91RM9200 only. Subsequent versions do not need this
workaround. This workaround unnecessarily resets RX whenever RX used
bit read is observed, which can be often under heavy traffic. There
is no other action performed on RX UBR interrupt. Hence introduce a
CAPS mask; enable this interrupt and workaround only on affected
versions.

Signed-off-by: Harini Katakam <harini.katakam@xilinx.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 17 insertions, 11 deletions

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 66cc7927061a..2b2882615e8b 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -56,8 +56,7 @@
 /* level of occupied TX descriptors under which we wake up TX process */
 #define MACB_TX_WAKEUP_THRESH(bp)	(3 * (bp)->tx_ring_size / 4)
 
-#define MACB_RX_INT_FLAGS	(MACB_BIT(RCOMP) | MACB_BIT(RXUBR)	\
-				 | MACB_BIT(ISR_ROVR))
+#define MACB_RX_INT_FLAGS	(MACB_BIT(RCOMP) | MACB_BIT(ISR_ROVR))
 #define MACB_TX_ERR_FLAGS	(MACB_BIT(ISR_TUND)			\
 					| MACB_BIT(ISR_RLE)		\
 					| MACB_BIT(TXERR))
@@ -1270,7 +1269,7 @@ static int macb_poll(struct napi_struct *napi, int budget)
 				queue_writel(queue, ISR, MACB_BIT(RCOMP));
 			napi_reschedule(napi);
 		} else {
-			queue_writel(queue, IER, MACB_RX_INT_FLAGS);
+			queue_writel(queue, IER, bp->rx_intr_mask);
 		}
 	}
 
@@ -1288,7 +1287,7 @@ static void macb_hresp_error_task(unsigned long data)
 	u32 ctrl;
 
 	for (q = 0, queue = bp->queues; q < bp->num_queues; ++q, ++queue) {
-		queue_writel(queue, IDR, MACB_RX_INT_FLAGS |
+		queue_writel(queue, IDR, bp->rx_intr_mask |
 					 MACB_TX_INT_FLAGS |
 					 MACB_BIT(HRESP));
 	}
@@ -1318,7 +1317,7 @@ static void macb_hresp_error_task(unsigned long data)
 
 		/* Enable interrupts */
 		queue_writel(queue, IER,
-			     MACB_RX_INT_FLAGS |
+			     bp->rx_intr_mask |
 			     MACB_TX_INT_FLAGS |
 			     MACB_BIT(HRESP));
 	}
@@ -1372,14 +1371,14 @@ static irqreturn_t macb_interrupt(int irq, void *dev_id)
 			    (unsigned int)(queue - bp->queues),
 			    (unsigned long)status);
 
-		if (status & MACB_RX_INT_FLAGS) {
+		if (status & bp->rx_intr_mask) {
 			/* There's no point taking any more interrupts
 			 * until we have processed the buffers. The
 			 * scheduling call may fail if the poll routine
 			 * is already scheduled, so disable interrupts
 			 * now.
 			 */
-			queue_writel(queue, IDR, MACB_RX_INT_FLAGS);
+			queue_writel(queue, IDR, bp->rx_intr_mask);
 			if (bp->caps & MACB_CAPS_ISR_CLEAR_ON_WRITE)
 				queue_writel(queue, ISR, MACB_BIT(RCOMP));
 
@@ -1412,8 +1411,9 @@ static irqreturn_t macb_interrupt(int irq, void *dev_id)
 		/* There is a hardware issue under heavy load where DMA can
 		 * stop, this causes endless "used buffer descriptor read"
 		 * interrupts but it can be cleared by re-enabling RX. See
-		 * the at91 manual, section 41.3.1 or the Zynq manual
-		 * section 16.7.4 for details.
+		 * the at91rm9200 manual, section 41.3.1 or the Zynq manual
+		 * section 16.7.4 for details. RXUBR is only enabled for
+		 * these two versions.
 		 */
 		if (status & MACB_BIT(RXUBR)) {
 			ctrl = macb_readl(bp, NCR);
@@ -2259,7 +2259,7 @@ static void macb_init_hw(struct macb *bp)
 
 		/* Enable interrupts */
 		queue_writel(queue, IER,
-			     MACB_RX_INT_FLAGS |
+			     bp->rx_intr_mask |
 			     MACB_TX_INT_FLAGS |
 			     MACB_BIT(HRESP));
 	}
@@ -3907,6 +3907,7 @@ static const struct macb_config sama5d4_config = {
 };
 
 static const struct macb_config emac_config = {
+	.caps = MACB_CAPS_NEEDS_RSTONUBR,
 	.clk_init = at91ether_clk_init,
 	.init = at91ether_init,
 };
@@ -3928,7 +3929,8 @@ static const struct macb_config zynqmp_config = {
 };
 
 static const struct macb_config zynq_config = {
-	.caps = MACB_CAPS_GIGABIT_MODE_AVAILABLE | MACB_CAPS_NO_GIGABIT_HALF,
+	.caps = MACB_CAPS_GIGABIT_MODE_AVAILABLE | MACB_CAPS_NO_GIGABIT_HALF |
+		MACB_CAPS_NEEDS_RSTONUBR,
 	.dma_burst_length = 16,
 	.clk_init = macb_clk_init,
 	.init = macb_init,
@@ -4083,6 +4085,10 @@ static int macb_probe(struct platform_device *pdev)
 						macb_dma_desc_get_size(bp);
 	}
 
+	bp->rx_intr_mask = MACB_RX_INT_FLAGS;
+	if (bp->caps & MACB_CAPS_NEEDS_RSTONUBR)
+		bp->rx_intr_mask |= MACB_BIT(RXUBR);
+
 	mac = of_get_mac_address(np);
 	if (mac) {
 		ether_addr_copy(bp->dev->dev_addr, mac);