linux-kernel - Re: [PATCH] i2c: imx: add support for I2C_M

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Message-ID: <20230727203045.2p7mbdtayca2hago@intel.intel>
Date:   Thu, 27 Jul 2023 22:30:45 +0200
From:   Andi Shyti <andi.shyti@...nel.org>
To:     Mans Rullgard <mans@...sr.com>
Cc:     Oleksij Rempel <linux@...pel-privat.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        linux-i2c@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] i2c: imx: add support for I2C_M_STOP flag

Hi Mans,

on top of Oleksij's comments...

[...]

> --- a/drivers/i2c/busses/i2c-imx.c
> +++ b/drivers/i2c/busses/i2c-imx.c
> @@ -1262,10 +1262,17 @@ static int i2c_imx_xfer_common(struct i2c_adapter *adapter,
>  
>  	/* read/write data */
>  	for (i = 0; i < num; i++) {
> -		if (i == num - 1)
> -			is_lastmsg = true;
> +		if (is_lastmsg) {
> +			/* previous message had I2C_M_STOP flag set */
> +			temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
> +			temp |= I2CR_MSTA;
> +			imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
> +			result = i2c_imx_bus_busy(i2c_imx, 1, atomic);
> +			if (result)
> +				goto fail0;
> +		}
>  
> -		if (i) {
> +		if (i && !is_lastmsg) {

	} else if (i) {

looks a bit simplier to me.

>  			dev_dbg(&i2c_imx->adapter.dev,
>  				"<%s> repeated start\n", __func__);
>  			temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
> @@ -1275,6 +1282,10 @@ static int i2c_imx_xfer_common(struct i2c_adapter *adapter,
>  			if (result)
>  				goto fail0;
>  		}
> +
> +		if (i == num - 1 || (msgs[i].flags & I2C_M_STOP))
> +			is_lastmsg = true;

you don't need this "i == num - 1" here.

Andi

>  		dev_dbg(&i2c_imx->adapter.dev,
>  			"<%s> transfer message: %d\n", __func__, i);
>  		/* write/read data */