Re: [PATCH V1 1/1] iio: Added Capella cm3232 ambient light sensor driver.

[Joe Perches <joe@perches.com>]

On Mon, 2015-01-05 at 12:51 +0200, Daniel Baluta wrote:
> On Thu, Jan 1, 2015 at 2:10 AM, Kevin Tsai <ktsai@capellamicro.com> wrote:
> > CM3232 is an advanced ambient light sensor with I2C protocol interface.
> > The I2C slave address is internally hardwired as 0x10 (7-bit).  Writing
> > to configure register is byte mode, but reading ALS register requests to
> > use word mode for 16-bit resolution.
> 
> This looks good to me.  Few comments inline.
[]
> > diff --git a/drivers/iio/light/cm3232.c b/drivers/iio/light/cm3232.c
[]
> > +/**
> > + * cm3232_reg_init() - Initialize CM3232 registers
> > + * @chip:      pointer of struct cm3232.
> > + *
> > + * Initialize CM3232 ambient light sensor register to default values.
> > + *
> > +  Return: 0 for success; otherwise for error code.
> > + */
> > +static int cm3232_reg_init(struct cm3232_chip *chip)
> > +{
> > +       struct i2c_client *client = chip->client;
> > +       struct cm3232_als_info *als_info;
> > +       s32 ret;
> > +
> > +       /* Identify device */
> > +       ret = i2c_smbus_read_word_data(client, CM3232_REG_ADDR_ID);
> > +       if (ret < 0)
> > +               return ret;
> > +       if ((ret & 0xFF) != 0x32)
> > +               return -ENODEV;
> > +
> > +       /* Disable and reset device */
> > +       chip->regs_cmd = CM3232_CMD_ALS_DISABLE | CM3232_CMD_ALS_RESET;
> > +       ret = i2c_smbus_write_byte_data(client, CM3232_REG_ADDR_CMD,
> > +                               chip->regs_cmd);
> > +       if (ret < 0)
> > +               return ret;
> > +
> > +       /* Initialization */
> > +       als_info = chip->als_info = &cm3232_als_info_default;
> > +       chip->regs_cmd = CM3232_CMD_DEFAULT;
> > +
> > +       /* Configure register */
> > +       ret = i2c_smbus_write_byte_data(client, CM3232_REG_ADDR_CMD,
> > +                               chip->regs_cmd);
> 
> You could directly return i2c_smbus_write_byte_data(..).

Sometimes it's better to return a specific value
for the error instead of depending on correctness
of all the indirect functions in the call chain.

In this case, all the smbus_xfer functions must
return 0 on success.  Do they?

Inspecting the codebase for correctness or not
depending on that correctness is sometimes better
to avoid doing.

> > +       if (ret < 0)
> > +               return ret;
> > +
> > +       return 0;
> > +}