Issue reading on I2C bus PMBUS device INA233

[MLa F.2]

STM32MP135 is connect on i2c bus to 3 devices:

• LM75
• PCF8563
• INA233

I am using linux kernel 5.15.24 synched with your github repo. LM75 and PCF8563 are working fine. INA233 has problems to manage the PEC (Packet Error Correction)

I am seeing lot of this errors:

stm32f7-i2c 40012000.i2c: Bad PEC 0x89 vs. 0x79

stm32f7-i2c 40012000.i2c: Bad PEC 0x89 vs. 0xc7

stm32f7-i2c 40012000.i2c: Bad PEC 0x89 vs. 0xed

I checked on the st driver that the PECEN is flagged since the i2c slave device has the PEC capability, and I am receving the PEC fo=rom the device in the log: 0x79, 0xcf, 0xed.

The strange think is that the register value read from stm device is always 0x89.

This value is read using the

internal_pec = readl_relaxed(i2c_dev->base + STM32F7_I2C_PECR)

It seems the register is not properly updated.

Any idea or suggestion?

[Bernard PUEL]

Could you please test this patch ? (it is based on kernel 6.10)

---
 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 97f7aced4f07..ff33a5e3e6e7 100644
--- a/drivers/i2c/busses/i2c-stm32f7.c
+++ b/drivers/i2c/busses/i2c-stm32f7.c
@@ -1071,9 +1071,10 @@ 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;
@@ -1161,8 +1162,10 @@ 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