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

The interrupt handler contains a workaround for RX hang applicable to Zynq and AT91 only. Subsequent versions do not need this workaround. Hence introduce an errata field and a check to enable this workaround only for Zynq (Can add further non-Xilinx devices after checking with mainline). A customer reported an issue when using this workaround on ZynqMP. RX used bit read (RXUBR) is observed whenever there's no free BDs. But if driver resets RX whenever this occurs, when the DMA clearly does not hang, there is a minute possibility that one of the RX BDs is skipped. Signed-off-by: Harini Katakam <[email protected]> Signed-off-by: Michal Simek <[email protected]>
slacrherbst · Nov 27, 2018 · acbe29b · acbe29b
1 parent 3248097
commit acbe29b
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Showing 2 changed files with 12 additions and 2 deletions.
diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
@@ -563,6 +563,9 @@
 #define MACB_CAPS_SG_DISABLED			0x40000000
 #define MACB_CAPS_MACB_IS_GEM			0x80000000
 
+/* Errata mask bits */
+#define MACB_ERRATA_RXLOCKUP			0x00000001
+
 /* LSO settings */
 #define MACB_LSO_UFO_ENABLE			0x01
 #define MACB_LSO_TSO_ENABLE			0x02
@@ -969,6 +972,7 @@ struct macb_config {
 			    struct clk **rx_clk, struct clk **tsu_clk);
 	int	(*init)(struct platform_device *pdev);
 	int	jumbo_max_len;
+	u32	errata;
 };
 
 struct tsu_incr {
@@ -1084,6 +1088,8 @@ struct macb {
 	struct ptp_clock_info ptp_clock_info;
 	struct tsu_incr tsu_incr;
 	struct hwtstamp_config tstamp_config;
+
+	u32 errata;
 };
 
 #ifdef CONFIG_MACB_USE_HWSTAMP

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
@@ -1438,7 +1438,8 @@ static irqreturn_t macb_interrupt(int irq, void *dev_id)
 		 * the at91 manual, section 41.3.1 or the Zynq manual
 		 * section 16.7.4 for details.
 		 */
-		if (status & MACB_BIT(RXUBR)) {
+		if ((bp->errata & MACB_ERRATA_RXLOCKUP) &&
+		    (status & MACB_BIT(RXUBR))) {
 			ctrl = macb_readl(bp, NCR);
 			macb_writel(bp, NCR, ctrl & ~MACB_BIT(RE));
 			wmb();
@@ -3587,6 +3588,7 @@ static const struct macb_config zynq_config = {
 	.dma_burst_length = 16,
 	.clk_init = macb_clk_init,
 	.init = macb_init,
+	.errata = MACB_ERRATA_RXLOCKUP,
 };
 
 static const struct of_device_id macb_dt_ids[] = {
@@ -3692,8 +3694,10 @@ static int macb_probe(struct platform_device *pdev)
 	if (tsu_clk)
 		bp->tsu_rate = clk_get_rate(tsu_clk);
 
-	if (macb_config)
+	if (macb_config) {
 		bp->jumbo_max_len = macb_config->jumbo_max_len;
+		bp->errata = macb_config->errata;
+	}
 
 	spin_lock_init(&bp->lock);