linux-kernel - Re: [PATCH v2 5/5] iio: dac: ad3552r-hs: add support for internal ramp

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Message-ID: <20250406102008.0ebcbf9e@jic23-huawei>
Date: Sun, 6 Apr 2025 10:20:08 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Angelo Dureghello <adureghello@...libre.com>
Cc: Nuno Sá <nuno.sa@...log.com>, Lars-Peter Clausen
 <lars@...afoo.de>, Jonathan Corbet <corbet@....net>, Olivier Moysan
 <olivier.moysan@...s.st.com>, Michael Hennerich
 <Michael.Hennerich@...log.com>, linux-iio@...r.kernel.org,
 linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 5/5] iio: dac: ad3552r-hs: add support for internal
 ramp

On Mon, 31 Mar 2025 21:02:48 +0200
Angelo Dureghello <adureghello@...libre.com> wrote:

> From: Angelo Dureghello <adureghello@...libre.com>
> 
> The ad3552r can be feeded from the HDL controller by an internally
> generated 16bit ramp, useful for debug pourposes. Add debugfs a file
> to enable or disable it.
> 
> Signed-off-by: Angelo Dureghello <adureghello@...libre.com>

A couple of really minor things inline.

> ---
>  drivers/iio/dac/ad3552r-hs.c | 122 ++++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 116 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/iio/dac/ad3552r-hs.c b/drivers/iio/dac/ad3552r-hs.c
> index 37397e188f225a8099745ec03f7c604da76960b1..d4f50b33565f99b90859e30571dc59038d01361c 100644
> --- a/drivers/iio/dac/ad3552r-hs.c
> +++ b/drivers/iio/dac/ad3552r-hs.c
> @@ -7,6 +7,7 @@
>   */
>  
>  #include <linux/bitfield.h>
> +#include <linux/debugfs.h>
>  #include <linux/delay.h>
>  #include <linux/gpio/consumer.h>
>  #include <linux/iio/backend.h>
> @@ -54,8 +55,12 @@ struct ad3552r_hs_state {
>  	struct ad3552r_hs_platform_data *data;
>  	/* INTERFACE_CONFIG_D register cache, in DDR we cannot read values. */
>  	u32 config_d;
> +	struct mutex lock;

Minor thing but all locks need comments.  What data is this lock protecting?

>  };
...

>  static int ad3552r_hs_probe(struct platform_device *pdev)
>  {
>  	struct ad3552r_hs_state *st;
> @@ -705,7 +806,16 @@ static int ad3552r_hs_probe(struct platform_device *pdev)
>  	if (ret)
>  		return ret;
>  
> -	return devm_iio_device_register(&pdev->dev, indio_dev);
> +	ret = devm_iio_device_register(&pdev->dev, indio_dev);
> +	if (ret)
> +		return ret;
> +
> +	mutex_init(&st->lock);
For new code, I'd prefer

	ret = devm_mutex_init(&st->lock);
	if (ret)
		return ret;

Brings only a small advantage, but give the complexity cost is also small
we might as well use it!

> +
> +	ad3552r_hs_debugfs_init(indio_dev);
> +
> +	return ret;
> +
>  }
>  
>  static const struct of_device_id ad3552r_hs_of_id[] = {
>