i2c: stm32f7: fix first byte to send in slave mode

The slave-interface documentation [1] states "the bus driver should
transmit the first byte" upon I2C_SLAVE_READ_REQUESTED slave event:
- 'val': backend returns first byte to be sent
The driver currently ignores the 1st byte to send on this event.

[1] https://www.kernel.org/doc/Documentation/i2c/slave-interface

Fixes: 60d609f ("i2c: i2c-stm32f7: Add slave support")
Signed-off-by: Fabrice Gasnier <[email protected]>
Reviewed-by: Pierre-Yves MORDRET <[email protected]>
Signed-off-by: Wolfram Sang <[email protected]>

Author: Fabrice Gasnier

drivers/i2c/busses/i2c-stm32f7.c

@@ -1192,6 +1192,8 @@ static void stm32f7_i2c_slave_start(struct stm32f7_i2c_dev *i2c_dev)
 			STM32F7_I2C_CR1_TXIE;
 		stm32f7_i2c_set_bits(base + STM32F7_I2C_CR1, mask);
 
+		/* Write 1st data byte */
+		writel_relaxed(value, base + STM32F7_I2C_TXDR);
 	} else {
 		/* Notify i2c slave that new write transfer is starting */
 		i2c_slave_event(slave, I2C_SLAVE_WRITE_REQUESTED, &value);