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

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Message-ID: <9ae3f111-e13b-cdd7-317d-316585390952@wanadoo.fr>
Date:   Sun, 14 May 2023 19:00:34 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Ondřej Jirman <megi@....cz>,
        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()

Le 14/05/2023 à 17:35, Ondřej Jirman a écrit :
> 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;

Ok, so moving reset_control_deassert() (and my proposed 
devm_add_action_or_reset()) just after devm_reset_control_get() should 
keep the expected order, right?

CJ

> 
> 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
>>
>