linux-kernel - Re: [PATCH] i2c: i2c-stm32f7: fix first byte to send in slave mode

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Message-ID: <144ffb23-a56e-c60f-8c50-802921755835@st.com>
Date:   Tue, 1 Oct 2019 09:10:14 +0200
From:   Pierre Yves MORDRET <pierre-yves.mordret@...com>
To:     Fabrice Gasnier <fabrice.gasnier@...com>, <wsa@...-dreams.de>
CC:     <alain.volmat@...com>, <alexandre.torgue@...com>,
        <linux-i2c@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] i2c: i2c-stm32f7: fix first byte to send in slave mode

Hi,

Reviewed-by: Pierre-Yves MORDRET <pierre-yves.mordret@...com>

Thx

On 9/30/19 5:28 PM, Fabrice Gasnier wrote:
> 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.
> 
> Fixes: 60d609f30de2 ("i2c: i2c-stm32f7: Add slave support")
> 
> [1] https://www.kernel.org/doc/Documentation/i2c/slave-interface
> 
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@...com>
> ---
>  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 266d1c2..0af9219 100644
> --- a/drivers/i2c/busses/i2c-stm32f7.c
> +++ b/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);
>