On Thu, 24 Mar 2022 15:29:28 -0700
Stephen Boyd <swboyd@xxxxxxxxxxxx> wrote:
> There are four possible gain values according to 'sx9324_gain_vals[]':
>
> 1, 2, 4, and 8
>
> The values are off by one when writing and reading the register. The
> bits should be set according to this equation:
>
> ilog2(<gain>) + 1
>
> so that a gain of 8 is 0x3 in the register field and a gain of 4 is 0x2
> in the register field, etc
Example seems wrong...
ilog2(8) + 1 = 3 + 1 = 0x4
ilog2(4) + 1 = 2 + 1 = 0x3
ilog2(2) + 1 = 1 + 1 = 0x2
ilog2(1) + 1 = 0 + 1 = 0x1
0x0 reserved.
or have I misunderstood?
>. Note that a gain of 0 is reserved per the
> datasheet. The default gain (SX9324_REG_PROX_CTRL0_GAIN_1) is also
> wrong. It should be 0x1 << 3, i.e. 0x8, not 0x80 which is setting the
> reserved bit 7.
>
> Fix this all up to properly handle the hardware gain and return errors
> for invalid settings.
>
> Fixes: 4c18a890dff8 ("iio:proximity:sx9324: Add SX9324 support")
> Cc: Gwendal Grignou <gwendal@xxxxxxxxxxxx>
> Signed-off-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
> ---
>
> Changes from v1 (https://lore.kernel.org/r/)20220318204808.3404542-1-swboyd@xxxxxxxxxxxx:
> * Reject invalid settings
> * Fix default value
> * More commit text details
>
> drivers/iio/proximity/sx9324.c | 26 +++++++++++++++++++++-----
> 1 file changed, 21 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/iio/proximity/sx9324.c b/drivers/iio/proximity/sx9324.c
> index 0d9bbbb50cb4..6e90917e3e36 100644
> --- a/drivers/iio/proximity/sx9324.c
> +++ b/drivers/iio/proximity/sx9324.c
> @@ -76,7 +76,10 @@
>
> #define SX9324_REG_PROX_CTRL0 0x30
> #define SX9324_REG_PROX_CTRL0_GAIN_MASK GENMASK(5, 3)
> -#define SX9324_REG_PROX_CTRL0_GAIN_1 0x80
> +#define SX9324_REG_PROX_CTRL0_GAIN_SHIFT 3
> +#define SX9324_REG_PROX_CTRL0_GAIN_RSVD 0x0
> +#define SX9324_REG_PROX_CTRL0_GAIN_1 0x1
> +#define SX9324_REG_PROX_CTRL0_GAIN_8 0x4
> #define SX9324_REG_PROX_CTRL0_RAWFILT_MASK GENMASK(2, 0)
> #define SX9324_REG_PROX_CTRL0_RAWFILT_1P50 0x01
> #define SX9324_REG_PROX_CTRL1 0x31
> @@ -379,7 +382,14 @@ static int sx9324_read_gain(struct sx_common_data *data,
> if (ret)
> return ret;
>
> - *val = 1 << FIELD_GET(SX9324_REG_PROX_CTRL0_GAIN_MASK, regval);
> + regval = FIELD_GET(SX9324_REG_PROX_CTRL0_GAIN_MASK, regval);
> + if (regval)
> + regval--;
> + else if (regval == SX9324_REG_PROX_CTRL0_GAIN_RSVD ||
> + regval > SX9324_REG_PROX_CTRL0_GAIN_8)
> + return -EINVAL;
> +
> + *val = 1 << regval;
>
> return IIO_VAL_INT;
> }
> @@ -725,8 +735,12 @@ static int sx9324_write_gain(struct sx_common_data *data,
> unsigned int gain, reg;
> int ret;
>
> - gain = ilog2(val);
> reg = SX9324_REG_PROX_CTRL0 + chan->channel / 2;
> +
> + gain = ilog2(val) + 1;
> + if (val <= 0 || gain > SX9324_REG_PROX_CTRL0_GAIN_8)
> + return -EINVAL;
> +
> gain = FIELD_PREP(SX9324_REG_PROX_CTRL0_GAIN_MASK, gain);
>
> mutex_lock(&data->mutex);
> @@ -784,9 +798,11 @@ static const struct sx_common_reg_default sx9324_default_regs[] = {
> { SX9324_REG_AFE_CTRL8, SX9324_REG_AFE_CTRL8_RESFILTN_4KOHM },
> { SX9324_REG_AFE_CTRL9, SX9324_REG_AFE_CTRL9_AGAIN_1 },
>
> - { SX9324_REG_PROX_CTRL0, SX9324_REG_PROX_CTRL0_GAIN_1 |
> + { SX9324_REG_PROX_CTRL0,
> + SX9324_REG_PROX_CTRL0_GAIN_1 << SX9324_REG_PROX_CTRL0_GAIN_SHIFT |
> SX9324_REG_PROX_CTRL0_RAWFILT_1P50 },
> - { SX9324_REG_PROX_CTRL1, SX9324_REG_PROX_CTRL0_GAIN_1 |
> + { SX9324_REG_PROX_CTRL1,
> + SX9324_REG_PROX_CTRL0_GAIN_1 << SX9324_REG_PROX_CTRL0_GAIN_SHIFT |
> SX9324_REG_PROX_CTRL0_RAWFILT_1P50 },
> { SX9324_REG_PROX_CTRL2, SX9324_REG_PROX_CTRL2_AVGNEG_THRESH_16K },
> { SX9324_REG_PROX_CTRL3, SX9324_REG_PROX_CTRL3_AVGDEB_2SAMPLES |
>
> base-commit: a8ee3b32f5da6c77a5ccc0e42c2250d61ba54fe0
