From: Clark Wang <xiaoning.wang@nxp.com>
Sent: Wednesday, March 17, 2021 2:54 PM

The clkhi and clklo ratio was not very precise before that can make the time of
START/STOP/HIGH LEVEL out of specification.

Therefore, the calculation of these times has been modified in this patch.
At the same time, the mode rate definition of i2c is corrected.

Reviewed-by: Fugang Duan <redacted>
Signed-off-by: Clark Wang <xiaoning.wang@nxp.com>
---
 drivers/i2c/busses/i2c-imx-lpi2c.c | 27 ++++++++++++++-------------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c

b/drivers/i2c/busses/i2c-imx-lpi2c.c
index 7216a393095d..5dbe85126f24 100644

--- a/drivers/i2c/busses/i2c-imx-lpi2c.c
+++ b/drivers/i2c/busses/i2c-imx-lpi2c.c

@@ -73,17 +73,17 @@
 #define MCFGR1_IGNACK	BIT(9)
 #define MRDR_RXEMPTY	BIT(14)

-#define I2C_CLK_RATIO	2
+#define I2C_CLK_RATIO	24 / 59

 #define CHUNK_DATA	256

 #define I2C_PM_TIMEOUT		1000 /* ms */

 enum lpi2c_imx_mode {
-	STANDARD,	/* 100+Kbps */
-	FAST,		/* 400+Kbps */
-	FAST_PLUS,	/* 1.0+Mbps */
-	HS,		/* 3.4+Mbps */
-	ULTRA_FAST,	/* 5.0+Mbps */
+	STANDARD,	/* <=100Kbps */
+	FAST,		/* <=400Kbps */
+	FAST_PLUS,	/* <=1.0Mbps */
+	HS,		/* <=3.4Mbps */
+	ULTRA_FAST,	/* <=5.0Mbps */
 };

 enum lpi2c_imx_pincfg {

@@ -156,13 +156,13 @@ static void lpi2c_imx_set_mode(struct

lpi2c_imx_struct *lpi2c_imx)
 	unsigned int bitrate = lpi2c_imx->bitrate;
 	enum lpi2c_imx_mode mode;

-	if (bitrate < I2C_MAX_FAST_MODE_FREQ)
+	if (bitrate <= I2C_MAX_STANDARD_MODE_FREQ)
 		mode = STANDARD;
-	else if (bitrate < I2C_MAX_FAST_MODE_PLUS_FREQ)
+	else if (bitrate <= I2C_MAX_FAST_MODE_FREQ)
 		mode = FAST;
-	else if (bitrate < I2C_MAX_HIGH_SPEED_MODE_FREQ)
+	else if (bitrate <= I2C_MAX_FAST_MODE_PLUS_FREQ)
 		mode = FAST_PLUS;
-	else if (bitrate < I2C_MAX_ULTRA_FAST_MODE_FREQ)
+	else if (bitrate <= I2C_MAX_HIGH_SPEED_MODE_FREQ)
 		mode = HS;
 	else
 		mode = ULTRA_FAST;

@@ -209,7 +209,8 @@ static void lpi2c_imx_stop(struct lpi2c_imx_struct

*lpi2c_imx)
 	} while (1);
 }

-/* CLKLO = I2C_CLK_RATIO * CLKHI, SETHOLD = CLKHI, DATAVD = CLKHI/2 */
+/* CLKLO = (1 - I2C_CLK_RATIO) * clk_cycle, SETHOLD = CLKHI, DATAVD =
CLKHI/2
+   CLKHI = I2C_CLK_RATIO * clk_cycle */
 static int lpi2c_imx_config(struct lpi2c_imx_struct *lpi2c_imx)  {
 	u8 prescale, filt, sethold, clkhi, clklo, datavd; @@ -232,8 +233,8 @@
static int lpi2c_imx_config(struct lpi2c_imx_struct *lpi2c_imx)

 	for (prescale = 0; prescale <= 7; prescale++) {
 		clk_cycle = clk_rate / ((1 << prescale) * lpi2c_imx->bitrate)
-			    - 3 - (filt >> 1);
-		clkhi = (clk_cycle + I2C_CLK_RATIO) / (I2C_CLK_RATIO + 1);
+			    - (2 + filt) / (1 << prescale);
+		clkhi = clk_cycle * I2C_CLK_RATIO;
 		clklo = clk_cycle - clkhi;
 		if (clklo < 64)
 			break;
--
2.25.1