linux-kernel - Re: [PATCH] i2c: mt76xx: add I2C_FUNC_NOSTART and I2C_M_REV_DIR

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Date:   Fri, 22 Oct 2021 08:44:24 +0200
From:   Stefan Roese <sr@...x.de>
To:     "zhaojh329@...il.com" <zhaojh329@...il.com>
Cc:     "matthias.bgg" <matthias.bgg@...il.com>,
        linux-i2c <linux-i2c@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-mediatek <linux-mediatek@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] i2c: mt76xx: add I2C_FUNC_NOSTART and I2C_M_REV_DIR_ADDR

On 19.10.21 18:07, zhaojh329@...il.com wrote:
>   This patch adds I2C_FUNC_NOSTART and I2C_M_REV_DIR_ADDR support for
> MediaTek MT7621/7628/7688. This is useful for some I2C slave chips,
> such as 'drivers/input/joystick/as5011.c'.
> 
> Signed-off-by: Jianhui Zhao <zhaojh329@...il.com>
> ---
>   drivers/i2c/busses/i2c-mt7621.c | 9 ++++++++-
>   1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/i2c/busses/i2c-mt7621.c b/drivers/i2c/busses/i2c-mt7621.c
> index 45fe4a7fe0c0..3d2763d9c090 100644
> --- a/drivers/i2c/busses/i2c-mt7621.c
> +++ b/drivers/i2c/busses/i2c-mt7621.c
> @@ -150,6 +150,9 @@ static int mtk_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
>   	for (i = 0; i < num; i++) {
>   		pmsg = &msgs[i];
>   
> +		if (pmsg->flags & I2C_M_NOSTART)
> +			goto nostart;
> +
>   		/* wait hardware idle */
>   		ret = mtk_i2c_wait_idle(i2c);
>   		if (ret)
> @@ -174,6 +177,8 @@ static int mtk_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
>   		} else {
>   			/* 7 bits address */
>   			addr = i2c_8bit_addr_from_msg(pmsg);
> +			if (pmsg->flags & I2C_M_REV_DIR_ADDR)
> +				addr ^= 1;
>   			iowrite32(addr, i2c->base + REG_SM0D0_REG);
>   			ret = mtk_i2c_master_cmd(i2c, SM0CTL1_WRITE, 1);
>   			if (ret)
> @@ -187,6 +192,7 @@ static int mtk_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
>   				goto err_ack;
>   		}
>   
> +nostart:
>   		/* transfer data */
>   		for (len = pmsg->len, j = 0; len > 0; len -= 8, j += 8) {
>   			page_len = (len >= 8) ? 8 : len;
> @@ -242,7 +248,8 @@ static int mtk_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
>   
>   static u32 mtk_i2c_func(struct i2c_adapter *a)
>   {
> -	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_PROTOCOL_MANGLING;
> +	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR
> +		| I2C_FUNC_PROTOCOL_MANGLING | I2C_FUNC_NOSTART;

Nit: I prefer to have the "|" at the end of the upper line instead of
adding it in the 2nd line.

Other that this:

Reviewed-by: Stefan Roese <sr@...x.de>

Thanks,
Stefan