linux-kernel - [PATCH] i2c: mediatek: fix transfer error handling

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Date:	Tue, 28 Jul 2015 11:38:05 +0800
From:	Eddie Huang <eddie.huang@...iatek.com>
To:	Wolfram Sang <wsa@...-dreams.de>
CC:	<srv_heupstream@...iatek.com>,
	Matthias Brugger <matthias.bgg@...il.com>,
	Liguo Zhang <liguo.zhang@...iatek.com>,
	Xudong Chen <xudong.chen@...iatek.com>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	<linux-i2c@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-mediatek@...ts.infradead.org>,
	Eddie Huang <eddie.huang@...iatek.com>
Subject: [PATCH] i2c: mediatek: fix transfer error handling

From: Liguo Zhang <liguo.zhang@...iatek.com>

Reset i2c dma engine in hw init function.
When occur i2c ack error, mtk_i2c_irq may is twice,
first is the ack error interrupt, then the complete interrupt,
so i2c->irq_stat need keep the two interrupt value, and only
call complete() for the complete interrupt.

Signed-off-by: Liguo Zhang <liguo.zhang@...iatek.com>
Signed-off-by: Eddie Huang <eddie.huang@...iatek.com>
---
 drivers/i2c/busses/i2c-mt65xx.c |   25 ++++++++++++++++++-------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c
index 9920eef..57d11b7 100644
--- a/drivers/i2c/busses/i2c-mt65xx.c
+++ b/drivers/i2c/busses/i2c-mt65xx.c
@@ -59,6 +59,7 @@
 #define I2C_DMA_START_EN		0x0001
 #define I2C_DMA_INT_FLAG_NONE		0x0000
 #define I2C_DMA_CLR_FLAG		0x0000
+#define I2C_DMA_HARD_RST		0x0002
 
 #define I2C_DEFAULT_SPEED		100000	/* hz */
 #define MAX_FS_MODE_SPEED		400000
@@ -81,6 +82,7 @@ enum DMA_REGS_OFFSET {
 	OFFSET_INT_FLAG = 0x0,
 	OFFSET_INT_EN = 0x04,
 	OFFSET_EN = 0x08,
+	OFFSET_RST = 0x0c,
 	OFFSET_CON = 0x18,
 	OFFSET_TX_MEM_ADDR = 0x1c,
 	OFFSET_RX_MEM_ADDR = 0x20,
@@ -262,6 +264,10 @@ static void mtk_i2c_init_hw(struct mtk_i2c *i2c)
 		      I2C_CONTROL_CLK_EXT_EN | I2C_CONTROL_DMA_EN;
 	writew(control_reg, i2c->base + OFFSET_CONTROL);
 	writew(I2C_DELAY_LEN, i2c->base + OFFSET_DELAY_LEN);
+
+	writel(I2C_DMA_HARD_RST, i2c->pdmabase + OFFSET_RST);
+	udelay(50);
+	writel(I2C_DMA_CLR_FLAG, i2c->pdmabase + OFFSET_RST);
 }
 
 /*
@@ -550,16 +556,20 @@ err_exit:
 static irqreturn_t mtk_i2c_irq(int irqno, void *dev_id)
 {
 	struct mtk_i2c *i2c = dev_id;
-	u16 restart_flag = 0;
+	u16 intr_stat = 0;
 
-	if (i2c->dev_comp->auto_restart)
-		restart_flag = I2C_RS_TRANSFER;
+	intr_stat = readw(i2c->base + OFFSET_INTR_STAT);
+	writew(intr_stat, i2c->base + OFFSET_INTR_STAT);
 
-	i2c->irq_stat = readw(i2c->base + OFFSET_INTR_STAT);
-	writew(restart_flag | I2C_HS_NACKERR | I2C_ACKERR
-		| I2C_TRANSAC_COMP, i2c->base + OFFSET_INTR_STAT);
+	/*
+	 * when occurs i2c ack error, mtk_i2c_irq is called twice,
+	 * first is the ack error interrupt, then the complete interrupt,
+	 * i2c->irq_stat need keep the two interrupt value.
+	 */
+	i2c->irq_stat |= intr_stat;
 
-	complete(&i2c->msg_complete);
+	if (i2c->irq_stat & I2C_TRANSAC_COMP)
+		complete(&i2c->msg_complete);
 
 	return IRQ_HANDLED;
 }
@@ -729,3 +739,4 @@ module_platform_driver(mtk_i2c_driver);
 MODULE_LICENSE("GPL v2");
 MODULE_DESCRIPTION("MediaTek I2C Bus Driver");
 MODULE_AUTHOR("Xudong Chen <xudong.chen@...iatek.com>");
+MODULE_AUTHOR("Liguo Zhang <liguo.zhang@...iatek.com>");
-- 
1.7.9.5

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