The PECBYTE bit allows to generate (in case of write) or
compute/compare the PEC byte (in case of read). In case
of reading a value (performed by first sending a write
command, then followed by a read command) the PECBYTE should
only be set before starting the read command and not before
the first write command.
Fixes: 9e48155f6bfe ("i2c: i2c-stm32f7: Add initial SMBus protocols support")
Signed-off-by: Alain Volmat <alain.volmat@xxxxxxxxxxx>
---
drivers/i2c/busses/i2c-stm32f7.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
index 579b30581725..0d3c9a041b56 100644
--- a/drivers/i2c/busses/i2c-stm32f7.c
+++ b/drivers/i2c/busses/i2c-stm32f7.c
@@ -1059,9 +1059,10 @@ static int stm32f7_i2c_smbus_xfer_msg(struct stm32f7_i2c_dev *i2c_dev,
/* Configure PEC */
if ((flags & I2C_CLIENT_PEC) && f7_msg->size != I2C_SMBUS_QUICK) {
cr1 |= STM32F7_I2C_CR1_PECEN;
- cr2 |= STM32F7_I2C_CR2_PECBYTE;
- if (!f7_msg->read_write)
+ if (!f7_msg->read_write) {
+ cr2 |= STM32F7_I2C_CR2_PECBYTE;
f7_msg->count++;
+ }
} else {
cr1 &= ~STM32F7_I2C_CR1_PECEN;
cr2 &= ~STM32F7_I2C_CR2_PECBYTE;
@@ -1149,8 +1150,10 @@ static void stm32f7_i2c_smbus_rep_start(struct stm32f7_i2c_dev *i2c_dev)
f7_msg->stop = true;
/* Add one byte for PEC if needed */
- if (cr1 & STM32F7_I2C_CR1_PECEN)
+ if (cr1 & STM32F7_I2C_CR1_PECEN) {
+ cr2 |= STM32F7_I2C_CR2_PECBYTE;
f7_msg->count++;
+ }
/* Set number of bytes to be transferred */
cr2 &= ~(STM32F7_I2C_CR2_NBYTES_MASK);
--
2.25.1
