Re: [PATCH 9/13] drivers/media/tuners/fc0011.c: use macros for i2c_msg initialization

[Julia Lawall <julia.lawall@xxxxxxx>]

On Sun, 7 Oct 2012, walter harms wrote:

> Am 07.10.2012 17:38, schrieb Julia Lawall:
> > From: Julia Lawall <Julia.Lawall@xxxxxxx>
> >
> > 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 in each case.
> >
> > 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@xxxxxxx>
> >
> > ---
> >  drivers/media/tuners/fc0011.c |    9 +++------
> >  1 file changed, 3 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/media/tuners/fc0011.c b/drivers/media/tuners/fc0011.c
> > index e488254..5dbba98 100644
> > --- a/drivers/media/tuners/fc0011.c
> > +++ b/drivers/media/tuners/fc0011.c
> > @@ -80,8 +80,7 @@ struct fc0011_priv {
> >  static int fc0011_writereg(struct fc0011_priv *priv, u8 reg, u8 val)
> >  {
> >  	u8 buf[2] = { reg, val };
> > -	struct i2c_msg msg = { .addr = priv->addr,
> > -		.flags = 0, .buf = buf, .len = 2 };
> > +	struct i2c_msg msg = I2C_MSG_WRITE(priv->addr, buf, sizeof(buf));
> >
> >  	if (i2c_transfer(priv->i2c, &msg, 1) != 1) {
> >  		dev_err(&priv->i2c->dev,
> > @@ -97,10 +96,8 @@ static int fc0011_readreg(struct fc0011_priv *priv, u8 reg, u8 *val)
> >  {
> >  	u8 dummy;
> >  	struct i2c_msg msg[2] = {
> > -		{ .addr = priv->addr,
> > -		  .flags = 0, .buf = &reg, .len = 1 },
> > -		{ .addr = priv->addr,
> > -		  .flags = I2C_M_RD, .buf = val ? : &dummy, .len = 1 },
> > +		I2C_MSG_WRITE(priv->addr, &reg, sizeof(reg)),
> > +		I2C_MSG_READ(priv->addr, val ? : &dummy, sizeof(dummy)),
> >  	};
>
> This dummy looks strange, can it be that this is used uninitialised ?

I'm not sure to understand the question.  The read, when it happens in 
i2c_transfer will initialize dummy.  On the other hand, I don't know what 
i2c_transfer does when the buffer is NULL and the size is 1.  It does not 
look very elegant at least.

julia
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