Re: [PATCH 12/13] iio: dac: ltc2688: Use __free(fwnode_handle) to replace fwnode_handle_put() calls

From: "Nuno Sá" <noname.nuno@gmail.com>
To: Jonathan Cameron <jic23@kernel.org>,
	linux-iio@vger.kernel.org,
	"Rafael J . Wysocki" <rafael@kernel.org>,
	Len Brown <lenb@kernel.org>,
	linux-acpi@vger.kernel.org,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Daniel Scally <djrscally@gmail.com>,
	Heikki Krogerus <heikki.krogerus@linux.intel.com>,
	Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: "Nuno Sá" <nuno.sa@analog.com>,
	"Cosmin Tanislav" <cosmin.tanislav@analog.com>,
	"Rasmus Villemoes" <linux@rasmusvillemoes.dk>,
	"Tomislav Denis" <tomislav.denis@avl.com>,
	"Marek Vasut" <marex@denx.de>,
	"Olivier Moysan" <olivier.moysan@foss.st.com>,
	"Fabrice Gasnier" <fabrice.gasnier@foss.st.com>,
	"Lad Prabhakar" <prabhakar.mahadev-lad.rj@bp.renesas.com>,
	"Dmitry Baryshkov" <dmitry.baryshkov@linaro.org>,
	"Marijn Suijten" <marijn.suijten@somainline.org>,
	"Marius Cristea" <marius.cristea@microchip.com>,
	"Ibrahim Tilki" <Ibrahim.Tilki@analog.com>,
	"Jonathan Cameron" <Jonathan.Cameron@huawei.com>
Subject: Re: [PATCH 12/13] iio: dac: ltc2688: Use __free(fwnode_handle) to replace fwnode_handle_put() calls
Date: Mon, 15 Jan 2024 11:26:25 +0100	[thread overview]
Message-ID: <ba1486e52fbf53e6199515df28b8e138b9bc3913.camel@gmail.com> (raw)
In-Reply-To: <20240114172009.179893-13-jic23@kernel.org>

On Sun, 2024-01-14 at 17:20 +0000, Jonathan Cameron wrote:
> From: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> 
> This use of the new cleanup.h scope based freeing infrastructure allows
> us to exit directly from error conditions within the
> device_for_each_child_node(dev, child) loop. On normal exit from that
> loop no fwnode_handle reference will be held and the child pointer
> will be NULL thus making the automatically run fwnode_handle_put() a
> noop.
> 
> Cc: Nuno Sá <nuno.sa@analog.com>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> ---

Just one minor comment on my side. With that:

Reviewed-by: Nuno Sa <nuno.sa@analog.com>

I might be able to give this a quick test. Let's see if I can find the time for
it :)

>  drivers/iio/dac/ltc2688.c | 23 ++++++-----------------
>  1 file changed, 6 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/iio/dac/ltc2688.c b/drivers/iio/dac/ltc2688.c
> index fc8eb53c65be..e8add3636af9 100644
> --- a/drivers/iio/dac/ltc2688.c
> +++ b/drivers/iio/dac/ltc2688.c
> @@ -746,7 +746,7 @@ static int ltc2688_span_lookup(const struct ltc2688_state
> *st, int min, int max)
>  static int ltc2688_channel_config(struct ltc2688_state *st)
>  {
>  	struct device *dev = &st->spi->dev;
> -	struct fwnode_handle *child;
> +	struct fwnode_handle *child __free(fwnode_handle) = NULL;
>  	u32 reg, clk_input, val, tmp[2];
>  	int ret, span;
>  
> @@ -754,18 +754,14 @@ static int ltc2688_channel_config(struct ltc2688_state
> *st)
>  		struct ltc2688_chan *chan;
>  
>  		ret = fwnode_property_read_u32(child, "reg", &reg);
> -		if (ret) {
> -			fwnode_handle_put(child);
> +		if (ret)
>  			return dev_err_probe(dev, ret,
>  					     "Failed to get reg property\n");
> -		}
>  
> -		if (reg >= LTC2688_DAC_CHANNELS) {
> -			fwnode_handle_put(child);
> +		if (reg >= LTC2688_DAC_CHANNELS)
>  			return dev_err_probe(dev, -EINVAL,
>  					     "reg bigger than: %d\n",
>  					     LTC2688_DAC_CHANNELS);
> -		}
>  
>  		val = 0;
>  		chan = &st->channels[reg];
> @@ -786,12 +782,10 @@ static int ltc2688_channel_config(struct ltc2688_state
> *st)
>  		if (!ret) {
>  			span = ltc2688_span_lookup(st, (int)tmp[0] / 1000,
>  						   tmp[1] / 1000);
> -			if (span < 0) {
> -				fwnode_handle_put(child);
> +			if (span < 0)
>  				return dev_err_probe(dev, -EINVAL,
>  						     "output range not
> valid:[%d %d]\n",
>  						     tmp[0], tmp[1]);
> -			}
>  
>  			val |= FIELD_PREP(LTC2688_CH_SPAN_MSK, span);
>  		}
> @@ -800,17 +794,14 @@ static int ltc2688_channel_config(struct ltc2688_state
> *st)
>  					       &clk_input);
>  		if (!ret) {
>  			if (clk_input >= LTC2688_CH_TGP_MAX) {

We can now remove the brackets...

> -				fwnode_handle_put(child);
>  				return dev_err_probe(dev, -EINVAL,
>  						     "toggle-dither-input inv
> value(%d)\n",
>  						     clk_input);
>  			}
>  
>  			ret = ltc2688_tgp_clk_setup(st, chan, child,
> clk_input);
> -			if (ret) {
> -				fwnode_handle_put(child);
> +			if (ret)
>  				return ret;
> -			}
>  
>  			/*
>  			 * 0 means software toggle which is the default mode.
> @@ -844,11 +835,9 @@ static int ltc2688_channel_config(struct ltc2688_state
> *st)
>  
>  		ret = regmap_write(st->regmap, LTC2688_CMD_CH_SETTING(reg),
>  				   val);
> -		if (ret) {
> -			fwnode_handle_put(child);
> +		if (ret)
>  			return dev_err_probe(dev, -EINVAL,
>  					     "failed to set chan
> settings\n");
> -		}
>  	}
>  
>  	return 0;