Re: [PATCH] iio: dac: ad9739a: write complete MU_CNT1 register during lock

[Jonathan Cameron <jic23@kernel.org>]

On Mon, 29 Apr 2024 15:54:39 +0200
Nuno Sa <nuno.sa@analog.com> wrote:

> As specified by the datasheet we should write the value 0x3 (enable
> plus tracking gain) into the MU_CNT1 register during the MU lock phase.
> 
> Currently we were only setting the enable bit (bit 0) as the tracking
> gain default value is already set to 1. While we should be mostly fine
> in assuming the tracking gain will have the value it should, better to
> explicitly write it. On top of that the datasheet also states to
> re-attempt the writes in case the lock fails which we were not doing for
> the tracking gain bit.
> 
> Lastly, the recommended value for the MU phase slope lock (bit 6) is 0
> but for some reason the default value is 1 and hence, we were not
> changing it accordingly.
> 
> Note there was no problem with the MU lock mechanism so this is not
> being treated as a fix but rather an improvement.
> 
> Signed-off-by: Nuno Sa <nuno.sa@analog.com>
Applied.

> ---
>  drivers/iio/dac/ad9739a.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/dac/ad9739a.c b/drivers/iio/dac/ad9739a.c
> index ff33120075bf..f56eabe53723 100644
> --- a/drivers/iio/dac/ad9739a.c
> +++ b/drivers/iio/dac/ad9739a.c
> @@ -45,6 +45,7 @@
>  #define AD9739A_REG_MU_DUTY		0x25
>  #define AD9739A_REG_MU_CNT1		0x26
>  #define   AD9739A_MU_EN_MASK		BIT(0)
> +#define   AD9739A_MU_GAIN_MASK		BIT(1)
>  #define AD9739A_REG_MU_CNT2		0x27
>  #define AD9739A_REG_MU_CNT3		0x28
>  #define AD9739A_REG_MU_CNT4		0x29
> @@ -220,8 +221,8 @@ static int ad9739a_init(struct device *dev, const struct ad9739a_state *st)
>  			return ret;
>  
>  		/* Enable the Mu controller search and track mode. */
> -		ret = regmap_set_bits(st->regmap, AD9739A_REG_MU_CNT1,
> -				      AD9739A_MU_EN_MASK);
> +		ret = regmap_write(st->regmap, AD9739A_REG_MU_CNT1,
> +				   AD9739A_MU_EN_MASK | AD9739A_MU_GAIN_MASK);
>  		if (ret)
>  			return ret;
>  
> 
> ---
> base-commit: b22457f6c572c1b453207d13613a4e476d3dd0fb
> change-id: 20240429-ad9739a-improv-adeda16e0dd5
> --
> 
> Thanks!
> - Nuno Sá
>