[PATCH v1 5/7] i2c: stm32f7: fix configuration of the digital filter

[Patrice Chotard]

From: Patrick Delaunay <patrick.delaunay at foss.st.com>

The digital filter related computation are present in the driver
however the programming of the filter within the IP is missing.
The maximum value for the DNF is wrong and should be 15 instead of 16.

Signed-off-by: Patrick Delaunay <patrick.delaunay at foss.st.com>
Signed-off-by: Patrice Chotard <patrice.chotard at foss.st.com>
---

 drivers/i2c/stm32f7_i2c.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/stm32f7_i2c.c b/drivers/i2c/stm32f7_i2c.c
index e71a0e0aa3..7e6c65fadc 100644
--- a/drivers/i2c/stm32f7_i2c.c
+++ b/drivers/i2c/stm32f7_i2c.c
@@ -45,6 +45,8 @@ struct stm32_i2c_regs {
 
 /* STM32 I2C control 1 */
 #define STM32_I2C_CR1_ANFOFF			BIT(12)
+#define STM32_I2C_CR1_DNF_MASK			GENMASK(11, 8)
+#define STM32_I2C_CR1_DNF(n)			(((n) & 0xf) << 8)
 #define STM32_I2C_CR1_ERRIE			BIT(7)
 #define STM32_I2C_CR1_TCIE			BIT(6)
 #define STM32_I2C_CR1_STOPIE			BIT(5)
@@ -106,7 +108,7 @@ struct stm32_i2c_regs {
 #define STM32_I2C_MAX_LEN			0xff
 
 #define STM32_I2C_DNF_DEFAULT			0
-#define STM32_I2C_DNF_MAX			16
+#define STM32_I2C_DNF_MAX			15
 
 #define STM32_I2C_ANALOG_FILTER_DELAY_MIN	50	/* ns */
 #define STM32_I2C_ANALOG_FILTER_DELAY_MAX	260	/* ns */
@@ -155,7 +157,7 @@ struct stm32_i2c_spec {
  * @clock_src: I2C clock source frequency (Hz)
  * @rise_time: Rise time (ns)
  * @fall_time: Fall time (ns)
- * @dnf: Digital filter coefficient (0-16)
+ * @dnf: value of digital filter to apply
  * @analog_filter: Analog filter delay (On/Off)
  */
 struct stm32_i2c_setup {
@@ -842,6 +844,10 @@ static int stm32_i2c_hw_config(struct stm32_i2c_priv *i2c_priv)
 	else
 		setbits_le32(&regs->cr1, STM32_I2C_CR1_ANFOFF);
 
+	/* Program the Digital Filter */
+	clrsetbits_le32(&regs->cr1, STM32_I2C_CR1_DNF_MASK,
+			STM32_I2C_CR1_DNF(i2c_priv->setup.dnf));
+
 	setbits_le32(&regs->cr1, STM32_I2C_CR1_PE);
 
 	return 0;
-- 
2.17.1