[PATCH 1/4] i2c: imx: check busy bit when START/STOP

[PATCH 1/4] i2c: imx: check busy bit when START/STOP

[Richard Zhao]

After START/RESTART, wait for busy bit to be set and
after STOP, wait for busy bit to be clear.

Signed-off-by: Richard Zhao <linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 4afba3e..156cc95 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -125,14 +125,19 @@ struct imx_i2c_struct {
 /** Functions for IMX I2C adapter driver ***************************************
 *******************************************************************************/
 
-static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx)
+static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy)
 {
 	unsigned long orig_jiffies = jiffies;
+	unsigned int temp;
 
 	dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
 
-	/* wait for bus not busy */
-	while (readb(i2c_imx->base + IMX_I2C_I2SR) & I2SR_IBB) {
+	temp = readb(i2c_imx->base + IMX_I2C_I2SR);
+	while (1) {
+		if (for_busy && (temp & I2SR_IBB))
+			break;
+		if (!for_busy && !(temp & I2SR_IBB))
+			break;
 		if (signal_pending(current)) {
 			dev_dbg(&i2c_imx->adapter.dev,
 				"<%s> I2C Interrupted\n", __func__);
@@ -144,6 +149,7 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx)
 			return -EIO;
 		}
 		schedule();
+		temp = readb(i2c_imx->base + IMX_I2C_I2SR);
 	}
 
 	return 0;
@@ -179,20 +185,32 @@ static int i2c_imx_acked(struct imx_i2c_struct *i2c_imx)
 	return 0;
 }
 
-static void i2c_imx_start(struct imx_i2c_struct *i2c_imx)
+static int i2c_imx_start(struct imx_i2c_struct *i2c_imx)
 {
 	unsigned int temp = 0;
+	int result;
 
 	dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
 
 	/* Enable I2C controller */
+	writeb(0, i2c_imx->base + IMX_I2C_I2SR);
 	writeb(I2CR_IEN, i2c_imx->base + IMX_I2C_I2CR);
+
+	result = i2c_imx_bus_busy(i2c_imx, 0);
+	if (result)
+		return result;
+
 	/* Start I2C transaction */
 	temp = readb(i2c_imx->base + IMX_I2C_I2CR);
 	temp |= I2CR_MSTA;
 	writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
+	result = i2c_imx_bus_busy(i2c_imx, 1);
+	if (result)
+		return result;
+
 	temp |= I2CR_IIEN | I2CR_MTX | I2CR_TXAK;
 	writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
+	return result;
 }
 
 static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx)
@@ -202,16 +220,16 @@ static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx)
 	/* Stop I2C transaction */
 	dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
 	temp = readb(i2c_imx->base + IMX_I2C_I2CR);
-	temp &= ~I2CR_MSTA;
+	temp &= ~(I2CR_MSTA | I2CR_MTX);
 	writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
-	/* setup chip registers to defaults */
-	writeb(I2CR_IEN, i2c_imx->base + IMX_I2C_I2CR);
-	writeb(0, i2c_imx->base + IMX_I2C_I2SR);
 	/*
 	 * This delay caused by an i.MXL hardware bug.
 	 * If no (or too short) delay, no "STOP" bit will be generated.
 	 */
 	udelay(i2c_imx->disable_delay);
+
+	i2c_imx_bus_busy(i2c_imx, 0);
+
 	/* Disable I2C controller */
 	writeb(0, i2c_imx->base + IMX_I2C_I2CR);
 }
@@ -344,7 +362,7 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs)
 			dev_dbg(&i2c_imx->adapter.dev,
 				"<%s> clear MSTA\n", __func__);
 			temp = readb(i2c_imx->base + IMX_I2C_I2CR);
-			temp &= ~I2CR_MSTA;
+			temp &= ~(I2CR_MSTA | I2CR_MTX);
 			writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
 		} else if (i == (msgs->len - 2)) {
 			dev_dbg(&i2c_imx->adapter.dev,
@@ -370,14 +388,11 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter,
 
 	dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
 
-	/* Check if i2c bus is not busy */
-	result = i2c_imx_bus_busy(i2c_imx);
+	/* Start I2C transfer */
+	result = i2c_imx_start(i2c_imx);
 	if (result)
 		goto fail0;
 
-	/* Start I2C transfer */
-	i2c_imx_start(i2c_imx);
-
 	/* read/write data */
 	for (i = 0; i < num; i++) {
 		if (i) {
@@ -386,6 +401,9 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter,
 			temp = readb(i2c_imx->base + IMX_I2C_I2CR);
 			temp |= I2CR_RSTA;
 			writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
+			result =  i2c_imx_bus_busy(i2c_imx, 1);
+			if (result)
+				goto fail0;
 		}
 		dev_dbg(&i2c_imx->adapter.dev,
 			"<%s> transfer message: %d\n", __func__, i);
-- 
1.6.0.4

[PATCH 2/4] i2c: imx: only imx1 needs disable delay

[Richard Zhao]

check cpu_is_mx1() when set disable_delay.

Signed-off-by: Richard Zhao <linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 156cc95..c1e541c 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -254,14 +254,16 @@ static void __init i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
 	/* Write divider value to register */
 	writeb(i2c_clk_div[i][1], i2c_imx->base + IMX_I2C_IFDR);
 
-	/*
-	 * There dummy delay is calculated.
-	 * It should be about one I2C clock period long.
-	 * This delay is used in I2C bus disable function
-	 * to fix chip hardware bug.
-	 */
-	i2c_imx->disable_delay = (500000U * i2c_clk_div[i][0]
-		+ (i2c_clk_rate / 2) - 1) / (i2c_clk_rate / 2);
+	if (cpu_is_mx1()) {
+		/*
+		 * There dummy delay is calculated.
+		 * It should be about one I2C clock period long.
+		 * This delay is used in I2C bus disable function
+		 * to fix chip hardware bug.
+		 */
+		i2c_imx->disable_delay = (500000U * i2c_clk_div[i][0]
+			+ (i2c_clk_rate / 2) - 1) / (i2c_clk_rate / 2);
+	}
 
 	/* dev_dbg() can't be used, because adapter is not yet registered */
 #ifdef CONFIG_I2C_DEBUG_BUS
-- 
1.6.0.4

[PATCH 3/4] i2c: imx: add macros and printk to make debug easy

[Richard Zhao]

When CONFIG_I2C_DEBUG_BUS is enabled, it helps dump registers at operation
fail condition, and print i2c_msg to xfer.

Signed-off-by: Richard Zhao <linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index c1e541c..87faea4 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -125,6 +125,20 @@ struct imx_i2c_struct {
 /** Functions for IMX I2C adapter driver ***************************************
 *******************************************************************************/
 
+#ifdef CONFIG_I2C_DEBUG_BUS
+#define reg_dump(i2c_imx) \
+{ \
+	printk(KERN_DEBUG "fun %s:%d ", __func__, __LINE__); \
+	printk(KERN_DEBUG "IADR %02x IFDR %02x I2CR %02x I2SR %02x\n", \
+		readb(i2c_imx->base + IMX_I2C_IADR), \
+		readb(i2c_imx->base + IMX_I2C_IFDR), \
+		readb(i2c_imx->base + IMX_I2C_I2CR), \
+		readb(i2c_imx->base + IMX_I2C_I2SR)); \
+}
+#else
+#define reg_dump(i2c_imx)
+#endif
+
 static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy)
 {
 	unsigned long orig_jiffies = jiffies;
@@ -146,6 +160,7 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy)
 		if (time_after(jiffies, orig_jiffies + HZ / 1000)) {
 			dev_dbg(&i2c_imx->adapter.dev,
 				"<%s> I2C bus is busy\n", __func__);
+			reg_dump(i2c_imx);
 			return -EIO;
 		}
 		schedule();
@@ -164,9 +179,11 @@ static int i2c_imx_trx_complete(struct imx_i2c_struct *i2c_imx)
 
 	if (unlikely(result < 0)) {
 		dev_dbg(&i2c_imx->adapter.dev, "<%s> result < 0\n", __func__);
+		reg_dump(i2c_imx);
 		return result;
 	} else if (unlikely(!(i2c_imx->i2csr & I2SR_IIF))) {
 		dev_dbg(&i2c_imx->adapter.dev, "<%s> Timeout\n", __func__);
+		reg_dump(i2c_imx);
 		return -ETIMEDOUT;
 	}
 	dev_dbg(&i2c_imx->adapter.dev, "<%s> TRX complete\n", __func__);
@@ -178,6 +195,7 @@ static int i2c_imx_acked(struct imx_i2c_struct *i2c_imx)
 {
 	if (readb(i2c_imx->base + IMX_I2C_I2SR) & I2SR_RXAK) {
 		dev_dbg(&i2c_imx->adapter.dev, "<%s> No ACK\n", __func__);
+		reg_dump(i2c_imx);
 		return -EIO;  /* No ACK */
 	}
 
@@ -197,17 +215,20 @@ static int i2c_imx_start(struct imx_i2c_struct *i2c_imx)
 	writeb(I2CR_IEN, i2c_imx->base + IMX_I2C_I2CR);
 
 	result = i2c_imx_bus_busy(i2c_imx, 0);
-	if (result)
+	if (result) {
+		reg_dump(i2c_imx);
 		return result;
+	}
 
 	/* Start I2C transaction */
 	temp = readb(i2c_imx->base + IMX_I2C_I2CR);
 	temp |= I2CR_MSTA;
 	writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
 	result = i2c_imx_bus_busy(i2c_imx, 1);
-	if (result)
+	if (result) {
+		reg_dump(i2c_imx);
 		return result;
-
+	}
 	temp |= I2CR_IIEN | I2CR_MTX | I2CR_TXAK;
 	writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
 	return result;
@@ -228,7 +249,8 @@ static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx)
 	 */
 	udelay(i2c_imx->disable_delay);
 
-	i2c_imx_bus_busy(i2c_imx, 0);
+	if (i2c_imx_bus_busy(i2c_imx, 0))
+		reg_dump(i2c_imx);
 
 	/* Disable I2C controller */
 	writeb(0, i2c_imx->base + IMX_I2C_I2CR);
@@ -389,7 +411,18 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter,
 	struct imx_i2c_struct *i2c_imx = i2c_get_adapdata(adapter);
 
 	dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
-
+#ifdef CONFIG_I2C_DEBUG_BUS
+	for (i = 0; i < num; i++) {
+		printk(KERN_DEBUG "msg%d addr %02x RD %d cnt %d d:", i,
+			msgs[i].addr, msgs[i].flags & I2C_M_RD, msgs[i].len);
+		if (!(msgs[i].flags & I2C_M_RD)) {
+			int j;
+			for (j = 0; j < msgs[i].len; j++)
+				printk("%02x ", msgs[i].buf[j]);
+		}
+		printk("\n");
+	}
+#endif
 	/* Start I2C transfer */
 	result = i2c_imx_start(i2c_imx);
 	if (result)
@@ -404,8 +437,10 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter,
 			temp |= I2CR_RSTA;
 			writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
 			result =  i2c_imx_bus_busy(i2c_imx, 1);
-			if (result)
+			if (result) {
+				reg_dump(i2c_imx);
 				goto fail0;
+			}
 		}
 		dev_dbg(&i2c_imx->adapter.dev,
 			"<%s> transfer message: %d\n", __func__, i);
@@ -562,7 +597,7 @@ static int __init i2c_imx_probe(struct platform_device *pdev)
 		res_size, i2c_imx->res->start);
 	dev_dbg(&i2c_imx->adapter.dev, "adapter name: \"%s\"\n",
 		i2c_imx->adapter.name);
-	dev_dbg(&i2c_imx->adapter.dev, "IMX I2C adapter registered\n");
+	dev_info(&i2c_imx->adapter.dev, "IMX I2C adapter registered\n");
 
 	return 0;   /* Return OK */
 
-- 
1.6.0.4

[PATCH 4/4] i2c: imx: disable clock when it's possible to save power.

[Richard Zhao]

Enable clock before START, disable it after STOP.

Signed-off-by: Richard Zhao <linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 87faea4..72ddea3 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -120,6 +120,7 @@ struct imx_i2c_struct {
 	wait_queue_head_t	queue;
 	unsigned long		i2csr;
 	unsigned int 		disable_delay;
+	unsigned int		ifdr; /* IMX_I2C_IFDR */
 };
 
 /** Functions for IMX I2C adapter driver ***************************************
@@ -210,6 +211,8 @@ static int i2c_imx_start(struct imx_i2c_struct *i2c_imx)
 
 	dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
 
+	clk_enable(i2c_imx->clk);
+	writeb(i2c_imx->ifdr, i2c_imx->base + IMX_I2C_IFDR);
 	/* Enable I2C controller */
 	writeb(0, i2c_imx->base + IMX_I2C_I2SR);
 	writeb(I2CR_IEN, i2c_imx->base + IMX_I2C_I2CR);
@@ -254,6 +257,7 @@ static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx)
 
 	/* Disable I2C controller */
 	writeb(0, i2c_imx->base + IMX_I2C_I2CR);
+	clk_disable(i2c_imx->clk);
 }
 
 static void __init i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
@@ -273,8 +277,8 @@ static void __init i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
 	else
 		for (i = 0; i2c_clk_div[i][0] < div; i++);
 
-	/* Write divider value to register */
-	writeb(i2c_clk_div[i][1], i2c_imx->base + IMX_I2C_IFDR);
+	/* Store divider value */
+	i2c_imx->ifdr = i2c_clk_div[i][1];
 
 	if (cpu_is_mx1()) {
 		/*
@@ -555,7 +559,6 @@ static int __init i2c_imx_probe(struct platform_device *pdev)
 		dev_err(&pdev->dev, "can't get I2C clock\n");
 		goto fail3;
 	}
-	clk_enable(i2c_imx->clk);
 
 	/* Request IRQ */
 	ret = request_irq(i2c_imx->irq, i2c_imx_isr, 0, pdev->name, i2c_imx);
@@ -604,7 +607,6 @@ static int __init i2c_imx_probe(struct platform_device *pdev)
 fail5:
 	free_irq(i2c_imx->irq, i2c_imx);
 fail4:
-	clk_disable(i2c_imx->clk);
 	clk_put(i2c_imx->clk);
 fail3:
 	release_mem_region(i2c_imx->res->start, resource_size(res));
@@ -641,8 +643,6 @@ static int __exit i2c_imx_remove(struct platform_device *pdev)
 	if (pdata && pdata->exit)
 		pdata->exit(&pdev->dev);
 
-	/* Disable I2C clock */
-	clk_disable(i2c_imx->clk);
 	clk_put(i2c_imx->clk);
 
 	release_mem_region(i2c_imx->res->start, resource_size(i2c_imx->res));
-- 
1.6.0.4

[PATCH 1/4] i2c: imx: check busy bit when START/STOP

[Richard Zhao]

After START/RESTART, wait for busy bit to be set and
after STOP, wait for busy bit to be clear.

Signed-off-by: Richard Zhao <linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 4afba3e..156cc95 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -125,14 +125,19 @@ struct imx_i2c_struct {
 /** Functions for IMX I2C adapter driver ***************************************
 *******************************************************************************/
 
-static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx)
+static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy)
 {
 	unsigned long orig_jiffies = jiffies;
+	unsigned int temp;
 
 	dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
 
-	/* wait for bus not busy */
-	while (readb(i2c_imx->base + IMX_I2C_I2SR) & I2SR_IBB) {
+	temp = readb(i2c_imx->base + IMX_I2C_I2SR);
+	while (1) {
+		if (for_busy && (temp & I2SR_IBB))
+			break;
+		if (!for_busy && !(temp & I2SR_IBB))
+			break;
 		if (signal_pending(current)) {
 			dev_dbg(&i2c_imx->adapter.dev,
 				"<%s> I2C Interrupted\n", __func__);
@@ -144,6 +149,7 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx)
 			return -EIO;
 		}
 		schedule();
+		temp = readb(i2c_imx->base + IMX_I2C_I2SR);
 	}
 
 	return 0;
@@ -179,20 +185,32 @@ static int i2c_imx_acked(struct imx_i2c_struct *i2c_imx)
 	return 0;
 }
 
-static void i2c_imx_start(struct imx_i2c_struct *i2c_imx)
+static int i2c_imx_start(struct imx_i2c_struct *i2c_imx)
 {
 	unsigned int temp = 0;
+	int result;
 
 	dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
 
 	/* Enable I2C controller */
+	writeb(0, i2c_imx->base + IMX_I2C_I2SR);
 	writeb(I2CR_IEN, i2c_imx->base + IMX_I2C_I2CR);
+
+	result = i2c_imx_bus_busy(i2c_imx, 0);
+	if (result)
+		return result;
+
 	/* Start I2C transaction */
 	temp = readb(i2c_imx->base + IMX_I2C_I2CR);
 	temp |= I2CR_MSTA;
 	writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
+	result = i2c_imx_bus_busy(i2c_imx, 1);
+	if (result)
+		return result;
+
 	temp |= I2CR_IIEN | I2CR_MTX | I2CR_TXAK;
 	writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
+	return result;
 }
 
 static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx)
@@ -202,16 +220,16 @@ static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx)
 	/* Stop I2C transaction */
 	dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
 	temp = readb(i2c_imx->base + IMX_I2C_I2CR);
-	temp &= ~I2CR_MSTA;
+	temp &= ~(I2CR_MSTA | I2CR_MTX);
 	writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
-	/* setup chip registers to defaults */
-	writeb(I2CR_IEN, i2c_imx->base + IMX_I2C_I2CR);
-	writeb(0, i2c_imx->base + IMX_I2C_I2SR);
 	/*
 	 * This delay caused by an i.MXL hardware bug.
 	 * If no (or too short) delay, no "STOP" bit will be generated.
 	 */
 	udelay(i2c_imx->disable_delay);
+
+	i2c_imx_bus_busy(i2c_imx, 0);
+
 	/* Disable I2C controller */
 	writeb(0, i2c_imx->base + IMX_I2C_I2CR);
 }
@@ -344,7 +362,7 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs)
 			dev_dbg(&i2c_imx->adapter.dev,
 				"<%s> clear MSTA\n", __func__);
 			temp = readb(i2c_imx->base + IMX_I2C_I2CR);
-			temp &= ~I2CR_MSTA;
+			temp &= ~(I2CR_MSTA | I2CR_MTX);
 			writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
 		} else if (i == (msgs->len - 2)) {
 			dev_dbg(&i2c_imx->adapter.dev,
@@ -370,14 +388,11 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter,
 
 	dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
 
-	/* Check if i2c bus is not busy */
-	result = i2c_imx_bus_busy(i2c_imx);
+	/* Start I2C transfer */
+	result = i2c_imx_start(i2c_imx);
 	if (result)
 		goto fail0;
 
-	/* Start I2C transfer */
-	i2c_imx_start(i2c_imx);
-
 	/* read/write data */
 	for (i = 0; i < num; i++) {
 		if (i) {
@@ -386,6 +401,9 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter,
 			temp = readb(i2c_imx->base + IMX_I2C_I2CR);
 			temp |= I2CR_RSTA;
 			writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
+			result =  i2c_imx_bus_busy(i2c_imx, 1);
+			if (result)
+				goto fail0;
 		}
 		dev_dbg(&i2c_imx->adapter.dev,
 			"<%s> transfer message: %d\n", __func__, i);
-- 
1.6.0.4

[PATCH 2/4] i2c: imx: only imx1 needs disable delay

[Richard Zhao]

check cpu_is_mx1() when set disable_delay.

Signed-off-by: Richard Zhao <linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 156cc95..c1e541c 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -254,14 +254,16 @@ static void __init i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
 	/* Write divider value to register */
 	writeb(i2c_clk_div[i][1], i2c_imx->base + IMX_I2C_IFDR);
 
-	/*
-	 * There dummy delay is calculated.
-	 * It should be about one I2C clock period long.
-	 * This delay is used in I2C bus disable function
-	 * to fix chip hardware bug.
-	 */
-	i2c_imx->disable_delay = (500000U * i2c_clk_div[i][0]
-		+ (i2c_clk_rate / 2) - 1) / (i2c_clk_rate / 2);
+	if (cpu_is_mx1()) {
+		/*
+		 * There dummy delay is calculated.
+		 * It should be about one I2C clock period long.
+		 * This delay is used in I2C bus disable function
+		 * to fix chip hardware bug.
+		 */
+		i2c_imx->disable_delay = (500000U * i2c_clk_div[i][0]
+			+ (i2c_clk_rate / 2) - 1) / (i2c_clk_rate / 2);
+	}
 
 	/* dev_dbg() can't be used, because adapter is not yet registered */
 #ifdef CONFIG_I2C_DEBUG_BUS
-- 
1.6.0.4

Re: [PATCH 2/4] i2c: imx: only imx1 needs disable delay

[Sascha Hauer]

On Thu, Oct 01, 2009 at 09:13:31AM +0800, Richard Zhao wrote:
> check cpu_is_mx1() when set disable_delay.
> 
> Signed-off-by: Richard Zhao <linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> 
> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> index 156cc95..c1e541c 100644
> --- a/drivers/i2c/busses/i2c-imx.c
> +++ b/drivers/i2c/busses/i2c-imx.c
> @@ -254,14 +254,16 @@ static void __init i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
>  	/* Write divider value to register */
>  	writeb(i2c_clk_div[i][1], i2c_imx->base + IMX_I2C_IFDR);
>  
> -	/*
> -	 * There dummy delay is calculated.
> -	 * It should be about one I2C clock period long.
> -	 * This delay is used in I2C bus disable function
> -	 * to fix chip hardware bug.
> -	 */
> -	i2c_imx->disable_delay = (500000U * i2c_clk_div[i][0]
> -		+ (i2c_clk_rate / 2) - 1) / (i2c_clk_rate / 2);
> +	if (cpu_is_mx1()) {
> +		/*
> +		 * There dummy delay is calculated.
> +		 * It should be about one I2C clock period long.
> +		 * This delay is used in I2C bus disable function
> +		 * to fix chip hardware bug.
> +		 */
> +		i2c_imx->disable_delay = (500000U * i2c_clk_div[i][0]
> +			+ (i2c_clk_rate / 2) - 1) / (i2c_clk_rate / 2);
> +	}

I think you should put the udelay(i2c_imx->disable_delay) in
cpu_is_mx1() rather than the calculation.

Sascha


-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

Re: [PATCH 2/4] i2c: imx: only imx1 needs disable delay

[Richard Zhao]

On Thu, Oct 1, 2009 at 3:26 PM, Sascha Hauer <s.hauer@pengutronix.de> wrote:
> On Thu, Oct 01, 2009 at 09:13:31AM +0800, Richard Zhao wrote:
>> check cpu_is_mx1() when set disable_delay.
>>
>> Signed-off-by: Richard Zhao <linuxzsc@gmail.com>
>>
>> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
>> index 156cc95..c1e541c 100644
>> --- a/drivers/i2c/busses/i2c-imx.c
>> +++ b/drivers/i2c/busses/i2c-imx.c
>> @@ -254,14 +254,16 @@ static void __init i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
>>       /* Write divider value to register */
>>       writeb(i2c_clk_div[i][1], i2c_imx->base + IMX_I2C_IFDR);
>>
>> -     /*
>> -      * There dummy delay is calculated.
>> -      * It should be about one I2C clock period long.
>> -      * This delay is used in I2C bus disable function
>> -      * to fix chip hardware bug.
>> -      */
>> -     i2c_imx->disable_delay = (500000U * i2c_clk_div[i][0]
>> -             + (i2c_clk_rate / 2) - 1) / (i2c_clk_rate / 2);
>> +     if (cpu_is_mx1()) {
>> +             /*
>> +              * There dummy delay is calculated.
>> +              * It should be about one I2C clock period long.
>> +              * This delay is used in I2C bus disable function
>> +              * to fix chip hardware bug.
>> +              */
>> +             i2c_imx->disable_delay = (500000U * i2c_clk_div[i][0]
>> +                     + (i2c_clk_rate / 2) - 1) / (i2c_clk_rate / 2);
>> +     }
>
> I think you should put the udelay(i2c_imx->disable_delay) in
> cpu_is_mx1() rather than the calculation.
>
> Sascha
>
>
> --
> Pengutronix e.K.                           |                             |
> Industrial Linux Solutions                 | http://www.pengutronix.de/  |
> Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
> Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |
>
Do you think udelay(0) wast any more time than if()?
And Could I get all you comments in a single patch loop?

Thanks
Richard

Re: [PATCH 2/4] i2c: imx: only imx1 needs disable delay

[Sascha Hauer]

On Thu, Oct 01, 2009 at 03:52:15PM +0800, Richard Zhao wrote:
> On Thu, Oct 1, 2009 at 3:26 PM, Sascha Hauer <s.hauer-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> wrote:
> > On Thu, Oct 01, 2009 at 09:13:31AM +0800, Richard Zhao wrote:
> >> check cpu_is_mx1() when set disable_delay.
> >>
> >> Signed-off-by: Richard Zhao <linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> >>
> >> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> >> index 156cc95..c1e541c 100644
> >> --- a/drivers/i2c/busses/i2c-imx.c
> >> +++ b/drivers/i2c/busses/i2c-imx.c
> >> @@ -254,14 +254,16 @@ static void __init i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
> >>       /* Write divider value to register */
> >>       writeb(i2c_clk_div[i][1], i2c_imx->base + IMX_I2C_IFDR);
> >>
> >> -     /*
> >> -      * There dummy delay is calculated.
> >> -      * It should be about one I2C clock period long.
> >> -      * This delay is used in I2C bus disable function
> >> -      * to fix chip hardware bug.
> >> -      */
> >> -     i2c_imx->disable_delay = (500000U * i2c_clk_div[i][0]
> >> -             + (i2c_clk_rate / 2) - 1) / (i2c_clk_rate / 2);
> >> +     if (cpu_is_mx1()) {
> >> +             /*
> >> +              * There dummy delay is calculated.
> >> +              * It should be about one I2C clock period long.
> >> +              * This delay is used in I2C bus disable function
> >> +              * to fix chip hardware bug.
> >> +              */
> >> +             i2c_imx->disable_delay = (500000U * i2c_clk_div[i][0]
> >> +                     + (i2c_clk_rate / 2) - 1) / (i2c_clk_rate / 2);
> >> +     }
> >
> > I think you should put the udelay(i2c_imx->disable_delay) in
> > cpu_is_mx1() rather than the calculation.
> >
> > Sascha
> >
> >
> > --
> > Pengutronix e.K.                           |                             |
> > Industrial Linux Solutions                 | http://www.pengutronix.de/  |
> > Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
> > Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |
> >
> Do you think udelay(0) wast any more time than if()?

if (cpu_is_mx1()) is optimized out by the compiler.

Sascha


-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |