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

[Julia Lawall]

On Sun, 7 Oct 2012, walter harms wrote:



Am 07.10.2012 17:38, schrieb Julia Lawall:
From: Julia Lawall <julia.law...@lip6.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 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.law...@lip6.fr>

---
 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
--
To unsubscribe from this list: send the line "unsubscribe linux-media" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html