linux-kernel - Re: [PATCH] thermal/drivers/sun8i: Fix some error handling paths in sun8i_ths

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Date:   Sun, 14 May 2023 17:35:37 +0200
From:   Ondřej Jirman <megi@....cz>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc:     Vasily Khoruzhick <anarsoul@...il.com>,
        Yangtao Li <tiny.windzz@...il.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Amit Kucheria <amitk@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>, Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Samuel Holland <samuel@...lland.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Maxime Ripard <mripard@...nel.org>,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-sunxi@...ts.linux.dev
Subject: Re: [PATCH] thermal/drivers/sun8i: Fix some error handling paths in
 sun8i_ths_probe()

Hello Christophe,

On Sun, May 14, 2023 at 05:21:35PM +0200, Christophe JAILLET wrote:
> 
> Should an error occur after calling sun8i_ths_resource_init() in the probe
> function, some resources need to be released, as already done in the
> .remove() function.
> 
> Switch to the devm_clk_get_enabled() helper and add a new devm_action to
> turn sun8i_ths_resource_init() into a fully managed function.
> 
> This fixes the issue and removes some LoC at the same time.
> 
> Fixes: dccc5c3b6f30 ("thermal/drivers/sun8i: Add thermal driver for H6/H5/H3/A64/A83T/R40")
> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> ---
> This changes the order of the release functions, but should be fine.
> ---
>  drivers/thermal/sun8i_thermal.c | 43 +++++++++------------------------
>  1 file changed, 12 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/thermal/sun8i_thermal.c b/drivers/thermal/sun8i_thermal.c
> index 793ddce72132..8f4c29bc85aa 100644
> --- a/drivers/thermal/sun8i_thermal.c
> +++ b/drivers/thermal/sun8i_thermal.c
> @@ -319,6 +319,11 @@ static int sun8i_ths_calibrate(struct ths_device *tmdev)
>  	return ret;
>  }
>  
> +static void sun8i_ths_reset_control_assert(void *data)
> +{
> +	reset_control_assert(data);
> +}
> +
>  static int sun8i_ths_resource_init(struct ths_device *tmdev)
>  {
>  	struct device *dev = tmdev->dev;
> @@ -339,13 +344,13 @@ static int sun8i_ths_resource_init(struct ths_device *tmdev)
>  		if (IS_ERR(tmdev->reset))
>  			return PTR_ERR(tmdev->reset);
>  
> -		tmdev->bus_clk = devm_clk_get(&pdev->dev, "bus");
> +		tmdev->bus_clk = devm_clk_get_enabled(&pdev->dev, "bus");
>  		if (IS_ERR(tmdev->bus_clk))
>  			return PTR_ERR(tmdev->bus_clk);
>  	}
>  
>  	if (tmdev->chip->has_mod_clk) {
> -		tmdev->mod_clk = devm_clk_get(&pdev->dev, "mod");
> +		tmdev->mod_clk = devm_clk_get_enabled(&pdev->dev, "mod");

This changes the recommeded order of reset release/clock enable steps, eg. A64
manual says:

	3.3.6.4. Gating and reset

	Make sure that the reset signal has been released before the release of
	module clock gating;

kind regards,
	o.

>  		if (IS_ERR(tmdev->mod_clk))
>  			return PTR_ERR(tmdev->mod_clk);
>  	}
> @@ -354,32 +359,20 @@ static int sun8i_ths_resource_init(struct ths_device *tmdev)
>  	if (ret)
>  		return ret;
>  
> -	ret = clk_prepare_enable(tmdev->bus_clk);
> +	ret = devm_add_action_or_reset(dev, sun8i_ths_reset_control_assert,
> +				       tmdev->reset);
>  	if (ret)
> -		goto assert_reset;
> +		return ret;
>  
>  	ret = clk_set_rate(tmdev->mod_clk, 24000000);
>  	if (ret)
> -		goto bus_disable;
> -
> -	ret = clk_prepare_enable(tmdev->mod_clk);
> -	if (ret)
> -		goto bus_disable;
> +		return ret;
>  
>  	ret = sun8i_ths_calibrate(tmdev);
>  	if (ret)
> -		goto mod_disable;
> +		return ret;
>  
>  	return 0;
> -
> -mod_disable:
> -	clk_disable_unprepare(tmdev->mod_clk);
> -bus_disable:
> -	clk_disable_unprepare(tmdev->bus_clk);
> -assert_reset:
> -	reset_control_assert(tmdev->reset);
> -
> -	return ret;
>  }
>  
>  static int sun8i_h3_thermal_init(struct ths_device *tmdev)
> @@ -530,17 +523,6 @@ static int sun8i_ths_probe(struct platform_device *pdev)
>  	return 0;
>  }
>  
> -static int sun8i_ths_remove(struct platform_device *pdev)
> -{
> -	struct ths_device *tmdev = platform_get_drvdata(pdev);
> -
> -	clk_disable_unprepare(tmdev->mod_clk);
> -	clk_disable_unprepare(tmdev->bus_clk);
> -	reset_control_assert(tmdev->reset);
> -
> -	return 0;
> -}
> -
>  static const struct ths_thermal_chip sun8i_a83t_ths = {
>  	.sensor_num = 3,
>  	.scale = 705,
> @@ -642,7 +624,6 @@ MODULE_DEVICE_TABLE(of, of_ths_match);
>  
>  static struct platform_driver ths_driver = {
>  	.probe = sun8i_ths_probe,
> -	.remove = sun8i_ths_remove,
>  	.driver = {
>  		.name = "sun8i-thermal",
>  		.of_match_table = of_ths_match,
> -- 
> 2.34.1
>