On Mon, 11 Sep 2023 17:29:50 +0300
Antoniu Miclaus <antoniu.miclaus@xxxxxxxxxx> wrote:
> According to the datasheet switching to a new channel function implies
> multiple steps.
>
> All functions must be selected for a minimum of 130 μs before changing
> to another function.
> The DAC_CODEx registers are not reset by changing channel functions.
> Prior to changing channel functions, it is recommended to set the DAC
> code to 0x0000 via the DAC_CODEx registers. Set the channel function
> to high impedance via the CH_FUNC_SETUPx registers before transitioning
> to the new channel function. After the new channel function is configured,
> it is recommended to wait 150 μs before updating the DAC code.
>
> Even though the channel switch is done at only at probe, where a device
> reset is performed, that does not guarantee that the steps prior
> changing to new channel function should be neglected.
>
> Signed-off-by: Antoniu Miclaus <antoniu.miclaus@xxxxxxxxxx>
Given description and lack of fixes tag, I'm not treating this as a fix.
Let me know if I should and provide a fixes tag in reply to this therad.
Applied to the togreg branch of iio.git and pushed out as testing.
Thanks,
Jonathan
> ---
> drivers/iio/addac/ad74413r.c | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)
>
> diff --git a/drivers/iio/addac/ad74413r.c b/drivers/iio/addac/ad74413r.c
> index 6b0e8218f150..7b9ebb481815 100644
> --- a/drivers/iio/addac/ad74413r.c
> +++ b/drivers/iio/addac/ad74413r.c
> @@ -441,12 +441,30 @@ static int ad74413r_set_channel_function(struct ad74413r_state *st,
> {
> int ret;
>
> + ret = regmap_update_bits(st->regmap,
> + AD74413R_REG_CH_FUNC_SETUP_X(channel),
> + AD74413R_CH_FUNC_SETUP_MASK,
> + CH_FUNC_HIGH_IMPEDANCE);
> + if (ret)
> + return ret;
> +
> + /* Set DAC code to 0 prior to changing channel function */
> + ret = ad74413r_set_channel_dac_code(st, channel, 0);
> + if (ret)
> + return ret;
> +
> + /* Delay required before transition to new desired mode */
> + usleep_range(130, 150);
> +
> ret = regmap_update_bits(st->regmap,
> AD74413R_REG_CH_FUNC_SETUP_X(channel),
> AD74413R_CH_FUNC_SETUP_MASK, func);
> if (ret)
> return ret;
>
> + /* Delay required before updating the new DAC code */
> + usleep_range(150, 170);
> +
> if (func == CH_FUNC_CURRENT_INPUT_LOOP_POWER)
> ret = regmap_set_bits(st->regmap,
> AD74413R_REG_ADC_CONFIG_X(channel),
