linux-kernel - Re: [PATCH] iio: frequency: Use SLEEP bit instead of RESET to disable output

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Message-ID: <20250418164040.0f103380@jic23-huawei>
Date: Fri, 18 Apr 2025 16:40:40 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Gabriel Shahrouzi <gshahrouzi@...il.com>
Cc: gregkh@...uxfoundation.org, lars@...afoo.de, linux-iio@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-staging@...ts.linux.dev,
 Michael.Hennerich@...log.com, skhan@...uxfoundation.org,
 linux-kernel-mentees@...ts.linux.dev, stable@...r.kernel.org
Subject: Re: [PATCH] iio: frequency: Use SLEEP bit instead of RESET to
 disable output

On Thu, 17 Apr 2025 09:54:34 -0400
Gabriel Shahrouzi <gshahrouzi@...il.com> wrote:

> According to the AD9832 datasheet (Table 10, D12 description), setting
> the RESET bit forces the phase accumulator to zero, which corresponds to
> a full-scale DC output, rather than disabling the output signal.
> 
> The correct way to disable the output and enter a low-power state is to
> set the AD9832_SLEEP bit (Table 10, D13 description), which powers down
> the internal DAC current sources and disables internal clocks.
> 
> Fixes: ea707584bac1 ("Staging: IIO: DDS: AD9832 / AD9835 driver")
> Cc: stable@...r.kernel.org
> Signed-off-by: Gabriel Shahrouzi <gshahrouzi@...il.com>
> ---
Seems reasonable but I'd like some more review of this before picking it up.
So feel free to poke me if nothing happens in say 2 weeks from now.

>  drivers/staging/iio/frequency/ad9832.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/iio/frequency/ad9832.c b/drivers/staging/iio/frequency/ad9832.c
> index db42810c7664b..0872ff4ec4896 100644
> --- a/drivers/staging/iio/frequency/ad9832.c
> +++ b/drivers/staging/iio/frequency/ad9832.c
> @@ -232,7 +232,7 @@ static ssize_t ad9832_write(struct device *dev, struct device_attribute *attr,
>  			st->ctrl_src &= ~(AD9832_RESET | AD9832_SLEEP |
>  					AD9832_CLR);
>  		else
> -			st->ctrl_src |= AD9832_RESET;
> +			st->ctrl_src |= AD9832_SLEEP;
>  
>  		st->data = cpu_to_be16((AD9832_CMD_SLEEPRESCLR << CMD_SHIFT) |
>  					st->ctrl_src);