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SubjectRe: [PATCH 05/11] staging: iio: adt7316: fix the dac read calculation
On Tue, 11 Dec 2018 17:54:57 -0700
Jeremy Fertic <jeremyfertic@gmail.com> wrote:

> The calculation of the current dac value is using the wrong bits of the
> dac lsb register. Create two macros to shift the lsb register value into
> lsb position, depending on whether the dac is 10 or 12 bit. Initialize
> data to 0 so, with an 8 bit dac, the msb register value can be bitwise
> ORed with data.
>
> Signed-off-by: Jeremy Fertic <jeremyfertic@gmail.com>
This looks good, but with the previous 2 patches under discussion I'll
hold this one for v2.

Thanks

Jonathan

> ---
> drivers/staging/iio/addac/adt7316.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/staging/iio/addac/adt7316.c b/drivers/staging/iio/addac/adt7316.c
> index eee7c04f93f4..b7d12d003ddc 100644
> --- a/drivers/staging/iio/addac/adt7316.c
> +++ b/drivers/staging/iio/addac/adt7316.c
> @@ -47,6 +47,8 @@
> #define ADT7516_MSB_AIN3 0xA
> #define ADT7516_MSB_AIN4 0xB
> #define ADT7316_DA_DATA_BASE 0x10
> +#define ADT7316_DA_10_BIT_LSB_SHIFT 6
> +#define ADT7316_DA_12_BIT_LSB_SHIFT 4
> #define ADT7316_DA_MSB_DATA_REGS 4
> #define ADT7316_LSB_DAC_A 0x10
> #define ADT7316_MSB_DAC_A 0x11
> @@ -1403,7 +1405,7 @@ static IIO_DEVICE_ATTR(ex_analog_temp_offset, 0644,
> static ssize_t adt7316_show_DAC(struct adt7316_chip_info *chip,
> int channel, char *buf)
> {
> - u16 data;
> + u16 data = 0;
> u8 msb, lsb, offset;
> int ret;
>
> @@ -1428,7 +1430,11 @@ static ssize_t adt7316_show_DAC(struct adt7316_chip_info *chip,
> if (ret)
> return -EIO;
>
> - data = (msb << offset) + (lsb & ((1 << offset) - 1));
> + if (chip->dac_bits == 12)
> + data = lsb >> ADT7316_DA_12_BIT_LSB_SHIFT;
> + else if (chip->dac_bits == 10)
> + data = lsb >> ADT7316_DA_10_BIT_LSB_SHIFT;
> + data |= msb << offset;
>
> return sprintf(buf, "%d\n", data);
> }

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