net-next: mediatek: add RX IRQ delay support

The PDMA engine used for RX allows IRQ aggregation. The patch sets up the
corresponding registers to aggregate 4 IRQs into one. Using aggregation
reduces the load on the core handling to a quarter thus reducing IRQ
latency and increasing RX performance by around 10%.
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

@@ -1861,9 +1861,11 @@ static int mtk_hw_init(struct mtk_eth *eth)
 	/* Enable RX VLan Offloading */
 	mtk_w32(eth, 1, MTK_CDMP_EG_CTRL);
 
+	/* enable interrupt delay for RX */
+	mtk_w32(eth, MTK_PDMA_DELAY_RX_DELAY, MTK_PDMA_DELAY_INT);
+
 	/* disable delay and normal interrupt */
 	mtk_w32(eth, 0, MTK_QDMA_DELAY_INT);
-	mtk_w32(eth, 0, MTK_PDMA_DELAY_INT);
 	mtk_irq_disable(eth, MTK_QDMA_INT_MASK, ~0);
 	mtk_irq_disable(eth, MTK_PDMA_INT_MASK, ~0);
 	mtk_w32(eth, RST_GL_PSE, MTK_RST_GL);

drivers/net/ethernet/mediatek/mtk_eth_soc.h

@@ -126,6 +126,13 @@
 
 /* PDMA Delay Interrupt Register */
 #define MTK_PDMA_DELAY_INT		0xa0c
+#define MTK_PDMA_DELAY_RX_EN		BIT(15)
+#define MTK_PDMA_DELAY_RX_PINT		4
+#define MTK_PDMA_DELAY_RX_PINT_SHIFT	8
+#define MTK_PDMA_DELAY_RX_PTIME		4
+#define MTK_PDMA_DELAY_RX_DELAY		\
+	(MTK_PDMA_DELAY_RX_EN | MTK_PDMA_DELAY_RX_PTIME | \
+	(MTK_PDMA_DELAY_RX_PINT << MTK_PDMA_DELAY_RX_PINT_SHIFT))
 
 /* PDMA Interrupt Status Register */
 #define MTK_PDMA_INT_STATUS	0xa20
@@ -206,6 +213,7 @@
 
 /* QDMA Interrupt Status Register */
 #define MTK_QMTK_INT_STATUS	0x1A18
+#define MTK_RX_DONE_DLY		BIT(30)
 #define MTK_RX_DONE_INT3	BIT(19)
 #define MTK_RX_DONE_INT2	BIT(18)
 #define MTK_RX_DONE_INT1	BIT(17)
@@ -214,8 +222,7 @@
 #define MTK_TX_DONE_INT2	BIT(2)
 #define MTK_TX_DONE_INT1	BIT(1)
 #define MTK_TX_DONE_INT0	BIT(0)
-#define MTK_RX_DONE_INT		(MTK_RX_DONE_INT0 | MTK_RX_DONE_INT1 | \
-				 MTK_RX_DONE_INT2 | MTK_RX_DONE_INT3)
+#define MTK_RX_DONE_INT		MTK_RX_DONE_DLY
 #define MTK_TX_DONE_INT		(MTK_TX_DONE_INT0 | MTK_TX_DONE_INT1 | \
 				 MTK_TX_DONE_INT2 | MTK_TX_DONE_INT3)