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From:   Harini Katakam <harini.katakam@xilinx.com>
To:     <nicolas.ferre@atmel.com>, <davem@davemloft.net>,
        <harinikatakamlinux@gmail.com>
CC:     <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <harinik@xilinx.com>, <michals@xilinx.com>,
        Harini Katakam <harini.katakam@xilinx.com>,
        Michal Simek <michal.simek@xilinx.com>
Subject: [RFC PATCH 3/3] net: macb: Handle HRESP error
Date:   Mon, 27 Nov 2017 13:07:18 +0530
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From: Harini Katakam <harini.katakam@xilinx.com>

Handle HRESP error by doing a SW reset of RX and TX and
re-initializing the descriptors, RX and TX queue pointers.

Signed-off-by: Harini Katakam <harinik@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
---
 drivers/net/ethernet/cadence/macb.h      |  2 +
 drivers/net/ethernet/cadence/macb_main.c | 65 ++++++++++++++++++++++++++++++--
 2 files changed, 63 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
index 974c801..5246ee1 100644
--- a/drivers/net/ethernet/cadence/macb.h
+++ b/drivers/net/ethernet/cadence/macb.h
@@ -1060,6 +1060,8 @@ struct macb {
 	struct ptp_clock_info ptp_clock_info;
 	struct tsu_incr tsu_incr;
 	struct hwtstamp_config tstamp_config;
+
+	struct tasklet_struct   hresp_err_tasklet;
 };
 
 #ifdef CONFIG_MACB_USE_HWSTAMP
diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index b14a04d..d76e04f 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -1244,6 +1244,63 @@ static int macb_poll(struct napi_struct *napi, int budget)
 	return work_done;
 }
 
+static void macb_hresp_error_task(unsigned long data)
+{
+	struct macb *bp = (struct macb *)data;
+	struct net_device *dev = bp->dev;
+	struct macb_queue *queue = bp->queues;
+	unsigned int q;
+	u32 ctrl;
+
+	for (q = 0, queue = bp->queues; q < bp->num_queues; ++q, ++queue) {
+		queue_writel(queue, IDR, MACB_RX_INT_FLAGS |
+					 MACB_TX_INT_FLAGS |
+					 MACB_BIT(HRESP));
+	}
+	ctrl = macb_readl(bp, NCR);
+	ctrl &= ~(MACB_BIT(RE) | MACB_BIT(TE));
+	macb_writel(bp, NCR, ctrl);
+
+	netif_tx_stop_all_queues(dev);
+	netif_carrier_off(dev);
+
+	bp->macbgem_ops.mog_init_rings(bp);
+
+	/* Initialize TX and RX buffers */
+	macb_writel(bp, RBQP, lower_32_bits(bp->rx_ring_dma));
+#ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT
+	if (bp->hw_dma_cap & HW_DMA_CAP_64B)
+		macb_writel(bp, RBQPH, upper_32_bits(bp->rx_ring_dma));
+#endif
+	for (q = 0, queue = bp->queues; q < bp->num_queues; ++q, ++queue) {
+		queue_writel(queue, TBQP, lower_32_bits(queue->tx_ring_dma));
+#ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT
+		if (bp->hw_dma_cap & HW_DMA_CAP_64B)
+			queue_writel(queue, TBQPH, upper_32_bits(queue->tx_ring_dma));
+#endif
+
+		/* We only use the first queue at the moment. Remaining
+		 * queues must be tied-off before we enable the receiver.
+		 *
+		 * See the documentation for receive_q1_ptr for more info.
+		 */
+		if (q)
+			queue_writel(queue, RBQP, bp->rx_ring_tieoff_dma);
+
+		/* Enable interrupts */
+		queue_writel(queue, IER,
+			     MACB_RX_INT_FLAGS |
+			     MACB_TX_INT_FLAGS |
+			     MACB_BIT(HRESP));
+	}
+
+	ctrl |= MACB_BIT(RE) | MACB_BIT(TE);
+	macb_writel(bp, NCR, ctrl);
+
+	netif_carrier_on(dev);
+	netif_tx_start_all_queues(dev);
+}
+
 static irqreturn_t macb_interrupt(int irq, void *dev_id)
 {
 	struct macb_queue *queue = dev_id;
@@ -1333,10 +1390,7 @@ static irqreturn_t macb_interrupt(int irq, void *dev_id)
 		}
 
 		if (status & MACB_BIT(HRESP)) {
-			/* TODO: Reset the hardware, and maybe move the
-			 * netdev_err to a lower-priority context as well
-			 * (work queue?)
-			 */
+			tasklet_schedule(&bp->hresp_err_tasklet);
 			netdev_err(dev, "DMA bus error: HRESP not OK\n");
 
 			if (bp->caps & MACB_CAPS_ISR_CLEAR_ON_WRITE)
@@ -3586,6 +3640,9 @@ static int macb_probe(struct platform_device *pdev)
 		goto err_out_unregister_mdio;
 	}
 
+	tasklet_init(&bp->hresp_err_tasklet, macb_hresp_error_task,
+		     (unsigned long)bp);
+
 	phy_attached_info(phydev);
 
 	netdev_info(dev, "Cadence %s rev 0x%08x at 0x%08lx irq %d (%pM)\n",
-- 
2.7.4


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