Re: [PATCH] i2c: Adding mangling capability to i2c imx bus controller.

[Wolfram Sang <w.sang@pengutronix.de>]

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Hi Fabien,

thanks for your patch. Nice addition.

On Mon, Jan 31, 2011 at 04:29:53PM +0100, Fabien Marteau wrote:
> Adding Mangling capability to i2c imx bus controller.

Can you give a rough description how you tested it?

> Signed-off-by: Fabien Marteau <fabien.marteau@armadeus.com>
> ---
> Index: linux-2.6.36/drivers/i2c/busses/i2c-imx.c
> ===================================================================
> --- linux-2.6.36.orig/drivers/i2c/busses/i2c-imx.c	2010-10-20 22:30:22.000000000 +0200
> +++ linux-2.6.36/drivers/i2c/busses/i2c-imx.c	2011-01-31 16:23:34.000000000 +0100
> @@ -300,17 +300,28 @@

Please use "--show-c-function" for diff/quilt. This makes reviewing a
tad easier.

>  {
>  	int i, result;
> 
> -	dev_dbg(&i2c_imx->adapter.dev, "<%s> write slave address: addr=0x%x\n",
> -		__func__, msgs->addr << 1);
> +	if ((msgs->flags & I2C_M_NOSTART) == 0) {

Please use !flag instead of == 0 as it is done in the rest of the
driver.

> +		/* write slave address */
> +		if (msgs->flags & I2C_M_REV_DIR_ADDR) {
> +			dev_dbg(&i2c_imx->adapter.dev,
> +				"<%s> write slave address: addr=0x%x\n",
> +				__func__, msgs->addr << 1 | 0x01);
> +			writeb((msgs->addr << 1) | 0x01,
> +			       i2c_imx->base + IMX_I2C_I2DR);
> +		} else {
> +			dev_dbg(&i2c_imx->adapter.dev,
> +				"<%s> write slave address: addr=0x%x\n",
> +				__func__, msgs->addr << 1);
> +			writeb((msgs->addr << 1), i2c_imx->base + IMX_I2C_I2DR);
> +		}

What about:

	dev_dbg();
	writeb(msgs->addr << 1 | !!(msg->flags & I2C_M_REV_DIR_ADDR));

Hmm, probably more readable would be

	write_flag = (msg->flags & I2C_M_REV_DIR_ADDR) ? I2C_SMBUS_READ : I2C_SMBUS_WRITE

and use that? Also, not sure about the additional dev_dbg.

> +		result = i2c_imx_trx_complete(i2c_imx);
> +		if (result)
> +			return result;
> +		result = i2c_imx_acked(i2c_imx);
> +		if (result != 0)

if (result)

> +			return result;
> +	}
> 
> -	/* write slave address */
> -	writeb(msgs->addr << 1, i2c_imx->base + IMX_I2C_I2DR);
> -	result = i2c_imx_trx_complete(i2c_imx);
> -	if (result)
> -		return result;
> -	result = i2c_imx_acked(i2c_imx);
> -	if (result)
> -		return result;
>  	dev_dbg(&i2c_imx->adapter.dev, "<%s> write data\n", __func__);
> 
>  	/* write data */
> @@ -323,7 +334,7 @@
>  		if (result)
>  			return result;
>  		result = i2c_imx_acked(i2c_imx);
> -		if (result)
> +		if ((result != 0) && ((msgs[0].flags & I2C_M_IGNORE_NAK) == 0))

if (result && !(msgs[0].flags & I2C_M_IGNORE_NAK))

>  			return result;
>  	}
>  	return 0;
> @@ -334,18 +345,27 @@
>  	int i, result;
>  	unsigned int temp;
> 
> -	dev_dbg(&i2c_imx->adapter.dev,
> -		"<%s> write slave address: addr=0x%x\n",
> -		__func__, (msgs->addr << 1) | 0x01);
> -
> -	/* write slave address */
> -	writeb((msgs->addr << 1) | 0x01, i2c_imx->base + IMX_I2C_I2DR);
> -	result = i2c_imx_trx_complete(i2c_imx);
> -	if (result)
> -		return result;
> -	result = i2c_imx_acked(i2c_imx);
> -	if (result)
> -		return result;
> +	if ((msgs->flags & I2C_M_NOSTART) == 0) {

!flag

> +		/* write slave address */
> +		if (msgs->flags & I2C_M_REV_DIR_ADDR) {
> +			dev_dbg(&i2c_imx->adapter.dev,
> +			"<%s> write slave address: addr=0x%x\n",
> +			__func__, (msgs->addr << 1));
> +			writeb((msgs->addr << 1), i2c_imx->base + IMX_I2C_I2DR);
> +		} else {
> +			dev_dbg(&i2c_imx->adapter.dev,
> +			"<%s> write slave address: addr=0x%x\n",
> +			__func__, (msgs->addr << 1) | 0x01);
> +			writeb((msgs->addr << 1) | 0x01,
> +			       i2c_imx->base + IMX_I2C_I2DR);
> +		}

Please fix similar to above.

> +		result = i2c_imx_trx_complete(i2c_imx);
> +		if (result)
> +			return result;
> +		result = i2c_imx_acked(i2c_imx);
> +		if (result != 0)

if (result)

> +			return result;
> +	}
> 
>  	dev_dbg(&i2c_imx->adapter.dev, "<%s> setup bus\n", __func__);
> 
> @@ -405,7 +425,7 @@
> 
>  	/* read/write data */
>  	for (i = 0; i < num; i++) {
> -		if (i) {
> +		if (i && ((msgs[i].flags & I2C_M_NOSTART) == 0)) {

if (i && !(flag))

(Please check for other occasions, I might have missed one)

>  			dev_dbg(&i2c_imx->adapter.dev,
>  				"<%s> repeated start\n", __func__);
>  			temp = readb(i2c_imx->base + IMX_I2C_I2CR);
> @@ -454,7 +474,7 @@
> 
>  static u32 i2c_imx_func(struct i2c_adapter *adapter)
>  {
> -	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
> +	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_PROTOCOL_MANGLING;
>  }
> 
>  static struct i2c_algorithm i2c_imx_algo = {
> --
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Regards,

   Wolfram

-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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