linux-kernel - Re: [PATCH 12/13] drivers/media/tuners/max2165.c: use macros for i2c

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Date:	Mon, 08 Oct 2012 09:14:25 +1100
From:	Ryan Mallon <rmallon@...il.com>
To:	Julia Lawall <Julia.Lawall@...6.fr>
CC:	Mauro Carvalho Chehab <mchehab@...radead.org>,
	kernel-janitors@...r.kernel.org, shubhrajyoti@...com,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 12/13] drivers/media/tuners/max2165.c: use macros for
 i2c_msg initialization

On 08/10/12 02:38, Julia Lawall wrote:
> From: Julia Lawall <Julia.Lawall@...6.fr>
> 
> Introduce use of I2c_MSG_READ/WRITE/OP, for readability.
> 
> A length expressed as an explicit constant is also re-expressed as the size
> of the buffer, when this is possible.
> 
> The second case is simplified to use simple variables rather than arrays.
> The variable b0 is dropped completely, and the variable reg that it
> contains is used instead.  The variable b1 is replaced by a u8-typed
> variable named buf (the name used earlier in the file).  The uses of b1 are
> then adjusted accordingly.
> 
> A simplified version of the semantic patch that makes this change is as
> follows: (http://coccinelle.lip6.fr/)
> 
> // <smpl>
> @@
> expression a,b,c;
> identifier x;
> @@
> 
> struct i2c_msg x =
> - {.addr = a, .buf = b, .len = c, .flags = I2C_M_RD}
> + I2C_MSG_READ(a,b,c)
>  ;
> 
> @@
> expression a,b,c;
> identifier x;
> @@
> 
> struct i2c_msg x =
> - {.addr = a, .buf = b, .len = c, .flags = 0}
> + I2C_MSG_WRITE(a,b,c)
>  ;
> 
> @@
> expression a,b,c,d;
> identifier x;
> @@
> 
> struct i2c_msg x = 
> - {.addr = a, .buf = b, .len = c, .flags = d}
> + I2C_MSG_OP(a,b,c,d)
>  ;
> // </smpl>
> 
> Signed-off-by: Julia Lawall <Julia.Lawall@...6.fr>
> 
> ---
> 
>  drivers/media/tuners/max2165.c |   13 ++++++-------
>  1 file changed, 6 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/media/tuners/max2165.c b/drivers/media/tuners/max2165.c
> index ba84936..6638617 100644
> --- a/drivers/media/tuners/max2165.c
> +++ b/drivers/media/tuners/max2165.c
> @@ -47,7 +47,7 @@ static int max2165_write_reg(struct max2165_priv *priv, u8 reg, u8 data)
>  {
>  	int ret;
>  	u8 buf[] = { reg, data };
> -	struct i2c_msg msg = { .flags = 0, .buf = buf, .len = 2 };
> +	struct i2c_msg msg = I2C_MSG_WRITE(0, buf, sizeof(buf));
>  
>  	msg.addr = priv->config->i2c_address;
>  
> @@ -68,11 +68,10 @@ static int max2165_read_reg(struct max2165_priv *priv, u8 reg, u8 *p_data)
>  	int ret;
>  	u8 dev_addr = priv->config->i2c_address;
>  
> -	u8 b0[] = { reg };
> -	u8 b1[] = { 0 };
> +	u8 buf;
>  	struct i2c_msg msg[] = {
> -		{ .addr = dev_addr, .flags = 0, .buf = b0, .len = 1 },
> -		{ .addr = dev_addr, .flags = I2C_M_RD, .buf = b1, .len = 1 },
> +		I2C_MSG_WRITE(dev_addr, &reg, sizeof(reg)),
> +		I2C_MSG_READ(dev_addr, &buf, sizeof(buf)),
>  	};

Not sure if the array changes should be done here or as a separate
patch. Some of the other patches also have cases where single index
arrays (both buffers and messages) could be converted. Should either
convert all or none of them. I think its probably best to do as a
separate series on top of this though.

~Ryan

>  
>  	ret = i2c_transfer(priv->i2c, msg, 2);
> @@ -81,10 +80,10 @@ static int max2165_read_reg(struct max2165_priv *priv, u8 reg, u8 *p_data)
>  		return -EIO;
>  	}
>  
> -	*p_data = b1[0];
> +	*p_data = buf;
>  	if (debug >= 2)
>  		dprintk("%s: reg=0x%02X, data=0x%02X\n",
> -			__func__, reg, b1[0]);
> +			__func__, reg, buf);
>  	return 0;
>  }
>  
> 

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