From: Fabrice Gasnier <fabrice.gasnier@xxxxxx> commit 915da2b794ce4fc98b1acf64d64354f22a5e4931 upstream 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@xxxxxx> Reviewed-by: Pierre-Yves MORDRET <pierre-yves.mordret@xxxxxx> Signed-off-by: Wolfram Sang <wsa@xxxxxxxxxxxxx> Cc: stable <stable@xxxxxxxxxxxxxxx> # 4.19+ Signed-off-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx> --- drivers/i2c/busses/i2c-stm32f7.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c index ac9c9486b834..48521bc8a4d2 100644 --- 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); -- 2.17.1
