linux-kernel - Re: [PATCH 2/7] watchdog: jz4740: Use devm

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Date:   Thu, 28 Dec 2017 20:59:27 +0100
From:   Paul Cercueil <paul@...pouillou.net>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Ralf Baechle <ralf@...ux-mips.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Wim Van Sebroeck <wim@...ana.be>, devicetree@...r.kernel.org,
        linux-mips@...ux-mips.org, linux-kernel@...r.kernel.org,
        linux-watchdog@...r.kernel.org
Subject: Re: [PATCH 2/7] watchdog: jz4740: Use devm_* functions

Hi Guenter,

Le jeu. 28 déc. 2017 à 18:48, Guenter Roeck <linux@...ck-us.net> a 
écrit :
> On 12/28/2017 08:29 AM, Paul Cercueil wrote:
>> - Use devm_clk_get instead of clk_get
>> - Use devm_watchdog_register_device instead of 
>> watchdog_register_device
>> 
>> Signed-off-by: Paul Cercueil <paul@...pouillou.net>
>> ---
>>   drivers/watchdog/jz4740_wdt.c | 27 ++++++++-------------------
>>   1 file changed, 8 insertions(+), 19 deletions(-)
>> 
>> diff --git a/drivers/watchdog/jz4740_wdt.c 
>> b/drivers/watchdog/jz4740_wdt.c
>> index 6955deb100ef..92d6ca8ceb49 100644
>> --- a/drivers/watchdog/jz4740_wdt.c
>> +++ b/drivers/watchdog/jz4740_wdt.c
>> @@ -178,40 +178,29 @@ static int jz4740_wdt_probe(struct 
>> platform_device *pdev)
>>     	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>   	drvdata->base = devm_ioremap_resource(&pdev->dev, res);
>> -	if (IS_ERR(drvdata->base)) {
>> -		ret = PTR_ERR(drvdata->base);
>> -		goto err_out;
>> -	}
>> +	if (IS_ERR(drvdata->base))
>> +		return PTR_ERR(drvdata->base);
>>   -	drvdata->rtc_clk = clk_get(&pdev->dev, "rtc");
>> +	drvdata->rtc_clk = devm_clk_get(&pdev->dev, "rtc");
>>   	if (IS_ERR(drvdata->rtc_clk)) {
>>   		dev_err(&pdev->dev, "cannot find RTC clock\n");
>> -		ret = PTR_ERR(drvdata->rtc_clk);
>> -		goto err_out;
>> +		return PTR_ERR(drvdata->rtc_clk);
>>   	}
>>   -	ret = watchdog_register_device(&drvdata->wdt);
>> +	ret = devm_watchdog_register_device(&pdev->dev, &drvdata->wdt);
>>   	if (ret < 0)
>> -		goto err_disable_clk;
>> +		return ret;
>>     	platform_set_drvdata(pdev, drvdata);
>> -	return 0;
>>   -err_disable_clk:
>> -	clk_put(drvdata->rtc_clk);
>> -err_out:
>> -	return ret;
>> +	return 0;
>>   }
>>     static int jz4740_wdt_remove(struct platform_device *pdev)
>>   {
>>   	struct jz4740_wdt_drvdata *drvdata = platform_get_drvdata(pdev);
>>   -	jz4740_wdt_stop(&drvdata->wdt);
>> -	watchdog_unregister_device(&drvdata->wdt);
>> -	clk_put(drvdata->rtc_clk);
>> -
>> -	return 0;
>> +	return jz4740_wdt_stop(&drvdata->wdt);
> 
> If the watchdog is running, the module can not be unloaded. Even if 
> that wasn't
> the case, this defeats both WDIOF_MAGICCLOSE and 
> watchdog_set_nowayout().
> Are you sure this is what you want ? If so, please call
> watchdog_stop_on_unregister() before registration; this clarifies 
> that this
> is what you want, and you can drop the remove function.
> 
> Thanks,
> Guenter

This patch does not change the behaviour. We always used that driver 
built-in; what
should the behaviour be when unloading the module? Keep the watchdog 
hardware running
if configured for 'nowayout'?

Thanks,
-Paul

> 
>>   }
>>     static struct platform_driver jz4740_wdt_driver = {
>> 
>