Re: [PATCH] i2c: Split I2C_M_NOSTART support out of I2C_FUNC_PROTOCOL_MANGLING

[Wolfram Sang <w.sang@xxxxxxxxxxxxxx>]

On Thu, Apr 26, 2012 at 01:37:19PM +0100, Mark Brown wrote:
> Since there are uses for I2C_M_NOSTART which are much more sensible and
> standard than most of the protocol mangling functionality (the main one
> being gather writes to devices where something like a register address
> needs to be inserted before a block of data) create a new I2C_FUNC_NOSTART
> for this feature and update all the users to use it.
> 
> In the case of regmap-i2c we remove the requirement for mangling as
> I2C_M_NOSTART is the only mangling feature which is being used.
> 
> Signed-off-by: Mark Brown <broonie@xxxxxxxxxxxxxxxxxxxxxxxxxxx>

In general, I like it. One thing below:

> --- a/include/linux/i2c.h
> +++ b/include/linux/i2c.h
> @@ -540,7 +540,7 @@ struct i2c_msg {
>  	__u16 flags;
>  #define I2C_M_TEN		0x0010	/* this is a ten bit chip address */
>  #define I2C_M_RD		0x0001	/* read data, from slave to master */
> -#define I2C_M_NOSTART		0x4000	/* if I2C_FUNC_PROTOCOL_MANGLING */
> +#define I2C_M_NOSTART		0x4000	/* if I2C_FUNC_NOSTART */
>  #define I2C_M_REV_DIR_ADDR	0x2000	/* if I2C_FUNC_PROTOCOL_MANGLING */
>  #define I2C_M_IGNORE_NAK	0x1000	/* if I2C_FUNC_PROTOCOL_MANGLING */
>  #define I2C_M_NO_RD_ACK		0x0800	/* if I2C_FUNC_PROTOCOL_MANGLING */
> @@ -568,6 +568,7 @@ struct i2c_msg {
>  #define I2C_FUNC_SMBUS_WRITE_BLOCK_DATA 0x02000000
>  #define I2C_FUNC_SMBUS_READ_I2C_BLOCK	0x04000000 /* I2C-like block xfer  */
>  #define I2C_FUNC_SMBUS_WRITE_I2C_BLOCK	0x08000000 /* w/ 1-byte reg. addr. */
> +#define I2C_FUNC_NOSTART		0x10000000 /* I2C_M_NOSTART */

In this file, the comment for MANGLING should be adapted, too. It says
currently:

#define I2C_FUNC_PROTOCOL_MANGLING      0x00000004 /* I2C_M_NOSTART etc. */

NOSTART is now out of MANGLING.

Also, I'd think the FUNC_NOSTART bit should be 0x08 and SMBUS_PEC 0x4000. This
will be more intuitive, probably?

Thanks,

   Wolfram

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