commit 7bc9ccec34f5260bf698de5d5c0366b6c6ef6c9e
author John Crispin <john@phrozen.org> Wed Jun 29 13:38:10 2016 +0200
committer David S. Miller <davem@davemloft.net> Thu Jun 30 08:52:04 2016 -0400
tree 0d6ab413668cf0c0d8366f5e45ee073234bdee63
parent eece71e8fb0953e18e3ac631b4414bb21af924a7

net-next: mediatek: add IRQ locking

The code that enables and disables IRQs is missing proper locking. After
adding the IRQ grouping patch and routing the RX and TX IRQs to 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.

Signed-off-by: John Crispin <john@phrozen.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mediatek/mtk_eth_soc.c

diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index d6c3a17..698caba 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -328,18 +328,24 @@
 
 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);
+	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);
+	spin_unlock_irqrestore(&eth->irq_lock, flags);
 }
 
 static int mtk_set_mac_address(struct net_device *dev, void *p)
@@ -1760,6 +1766,7 @@
 		return PTR_ERR(eth->base);
 
 	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");