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

[ Upstream commit 02e64276c6dbcc4c5f39844f33d18180832a58f3 ]

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: 60d609f30de2 ("i2c: i2c-stm32f7: Add slave support")
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Reviewed-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
index ac9c948..48521bc 100644 (file)
--- a/drivers/i2c/busses/i2c-stm32f7.c
+++ b/drivers/i2c/busses/i2c-stm32f7.c
@@ -1177,6 +1177,8 @@ 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);