openwrt/target/linux/mediatek/patches-4.4/0087-net-next-mediatek-add-IRQ-locking.patch

From 4ff9304355036d4a00bdf0e47e869fc770ba1cc5 Mon Sep 17 00:00:00 2001
From: John Crispin <blogic@openwrt.org>
Date: Wed, 20 Apr 2016 16:18:07 +0200
Subject: [PATCH 87/91] net-next: mediatek: add IRQ locking

The code that enables and disables IRQs is missing proper locking. After
adding the IRQ separation patch and routing the putting the RX and TX IRQs
on different cores we experienced IRQ stalls. Fix this by adding proper
locking. We use a dedicated lock to reduce the latency if the IRQ code.
Otherwise it might wait for bottom code to finish before reenabling or
disabling IRQs.

Signed-off-by: John Crispin <blogic@openwrt.org>
---
 drivers/net/ethernet/mediatek/mtk_eth_soc.c |    7 +++++++
 drivers/net/ethernet/mediatek/mtk_eth_soc.h |    1 +
 2 files changed, 8 insertions(+)

--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -316,22 +316,28 @@ static void mtk_mdio_cleanup(struct mtk_
 
 static inline void mtk_irq_disable(struct mtk_eth *eth, u32 mask)
 {
+	unsigned long flags;
 	u32 val;
 
+	spin_lock_irqsave(&eth->irq_lock, flags);
 	val = mtk_r32(eth, MTK_QDMA_INT_MASK);
 	mtk_w32(eth, val & ~mask, MTK_QDMA_INT_MASK);
 	/* flush write */
 	mtk_r32(eth, MTK_QDMA_INT_MASK);
+	spin_unlock_irqrestore(&eth->irq_lock, flags);
 }
 
 static inline void mtk_irq_enable(struct mtk_eth *eth, u32 mask)
 {
+	unsigned long flags;
 	u32 val;
 
+	spin_lock_irqsave(&eth->irq_lock, flags);
 	val = mtk_r32(eth, MTK_QDMA_INT_MASK);
 	mtk_w32(eth, val | mask, MTK_QDMA_INT_MASK);
 	/* flush write */
 	mtk_r32(eth, MTK_QDMA_INT_MASK);
+	spin_unlock_irqrestore(&eth->irq_lock, flags);
 }
 
 static int mtk_set_mac_address(struct net_device *dev, void *p)
@@ -1752,6 +1758,7 @@ static int mtk_probe(struct platform_dev
 		return -EADDRNOTAVAIL;
 
 	spin_lock_init(&eth->page_lock);
+	spin_lock_init(&eth->irq_lock);
 
 	eth->ethsys = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
 						      "mediatek,ethsys");
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.h
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
@@ -372,6 +372,7 @@ struct mtk_eth {
 	void __iomem			*base;
 	struct reset_control		*rstc;
 	spinlock_t			page_lock;
+	spinlock_t			irq_lock;
 	struct net_device		dummy_dev;
 	struct net_device		*netdev[MTK_MAX_DEVS];
 	struct mtk_mac			*mac[MTK_MAX_DEVS];