1 files changed, 37 insertions, 7 deletions

diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
index 21fbb340ad6..ad46616de29 100644
--- a/drivers/i2c/busses/i2c-designware-core.c
+++ b/drivers/i2c/busses/i2c-designware-core.c
@@ -67,9 +67,12 @@
 #define DW_IC_STATUS		0x70
 #define DW_IC_TXFLR		0x74
 #define DW_IC_RXFLR		0x78
+#define DW_IC_SDA_HOLD		0x7c
 #define DW_IC_TX_ABRT_SOURCE	0x80
 #define DW_IC_ENABLE_STATUS	0x9c
 #define DW_IC_COMP_PARAM_1	0xf4
+#define DW_IC_COMP_VERSION	0xf8
+#define DW_IC_SDA_HOLD_MIN_VERS	0x3131312A
 #define DW_IC_COMP_TYPE		0xfc
 #define DW_IC_COMP_TYPE_VALUE	0x44570140
 
@@ -332,6 +335,16 @@ int i2c_dw_init(struct dw_i2c_dev *dev)
 	dw_writel(dev, lcnt, DW_IC_FS_SCL_LCNT);
 	dev_dbg(dev->dev, "Fast-mode HCNT:LCNT = %d:%d\n", hcnt, lcnt);
 
+	/* Configure SDA Hold Time if required */
+	if (dev->sda_hold_time) {
+		reg = dw_readl(dev, DW_IC_COMP_VERSION);
+		if (reg >= DW_IC_SDA_HOLD_MIN_VERS)
+			dw_writel(dev, dev->sda_hold_time, DW_IC_SDA_HOLD);
+		else
+			dev_warn(dev->dev,
+				"Hardware too old to adjust SDA hold time.");
+	}
+
 	/* Configure Tx/Rx FIFO threshold levels */
 	dw_writel(dev, dev->tx_fifo_depth - 1, DW_IC_TX_TL);
 	dw_writel(dev, 0, DW_IC_RX_TL);
@@ -383,7 +396,8 @@ static void i2c_dw_xfer_init(struct dw_i2c_dev *dev)
 	/* Enable the adapter */
 	__i2c_dw_enable(dev, true);
 
-	/* Enable interrupts */
+	/* Clear and enable interrupts */
+	i2c_dw_clear_int(dev);
 	dw_writel(dev, DW_IC_INTR_DEFAULT_MASK, DW_IC_INTR_MASK);
 }
 
@@ -448,8 +462,14 @@ i2c_dw_xfer_msg(struct dw_i2c_dev *dev)
 				cmd |= BIT(9);
 
 			if (msgs[dev->msg_write_idx].flags & I2C_M_RD) {
+
+				/* avoid rx buffer overrun */
+				if (rx_limit - dev->rx_outstanding <= 0)
+					break;
+
 				dw_writel(dev, cmd | 0x100, DW_IC_DATA_CMD);
 				rx_limit--;
+				dev->rx_outstanding++;
 			} else
 				dw_writel(dev, cmd | *buf++, DW_IC_DATA_CMD);
 			tx_limit--; buf_len--;
@@ -502,8 +522,10 @@ i2c_dw_read(struct dw_i2c_dev *dev)
 
 		rx_valid = dw_readl(dev, DW_IC_RXFLR);
 
-		for (; len > 0 && rx_valid > 0; len--, rx_valid--)
+		for (; len > 0 && rx_valid > 0; len--, rx_valid--) {
 			*buf++ = dw_readl(dev, DW_IC_DATA_CMD);
+			dev->rx_outstanding--;
+		}
 
 		if (len > 0) {
 			dev->status |= STATUS_READ_IN_PROGRESS;
@@ -561,6 +583,7 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 	dev->msg_err = 0;
 	dev->status = STATUS_IDLE;
 	dev->abort_source = 0;
+	dev->rx_outstanding = 0;
 
 	ret = i2c_dw_wait_bus_not_busy(dev);
 	if (ret < 0)
@@ -570,14 +593,23 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 	i2c_dw_xfer_init(dev);
 
 	/* wait for tx to complete */
-	ret = wait_for_completion_interruptible_timeout(&dev->cmd_complete, HZ);
+	ret = wait_for_completion_timeout(&dev->cmd_complete, HZ);
 	if (ret == 0) {
 		dev_err(dev->dev, "controller timed out\n");
+		/* i2c_dw_init implicitly disables the adapter */
 		i2c_dw_init(dev);
 		ret = -ETIMEDOUT;
 		goto done;
-	} else if (ret < 0)
-		goto done;
+	}
+
+	/*
+	 * We must disable the adapter before unlocking the &dev->lock mutex
+	 * below. Otherwise the hardware might continue generating interrupts
+	 * which in turn causes a race condition with the following transfer.
+	 * Needs some more investigation if the additional interrupts are
+	 * a hardware bug or this driver doesn't handle them correctly yet.
+	 */
+	__i2c_dw_enable(dev, false);
 
 	if (dev->msg_err) {
 		ret = dev->msg_err;
@@ -586,8 +618,6 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 
 	/* no error */
 	if (likely(!dev->cmd_err)) {
-		/* Disable the adapter */
-		__i2c_dw_enable(dev, false);
 		ret = num;
 		goto done;
 	}