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

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Message-ID: <de7b629e-35b6-a55c-d7ca-57c145fa30ae@roeck-us.net>
Date:   Thu, 28 Dec 2017 13:03:35 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Paul Cercueil <paul@...pouillou.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

On 12/28/2017 12:22 PM, Paul Cercueil wrote:
> 
> 
> Le jeu. 28 déc. 2017 à 21:19, Guenter Roeck <linux@...ck-us.net> a écrit :
>> On 12/28/2017 11:59 AM, Paul Cercueil wrote:
>>> 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'?
>>>
>>
>> One can still unload the driver. If you are fine with bypassing/dfeating nowayout
>> and WDIOF_MAGICCLOSE, may I ask why those are enabled in the first place ?
>>
> 
> Who knows? That code is very old :)

Probably copied from some other driver w/o thinking much about it.

> I'm fine with removing the remove() function completely, if you think it makes more sense.
> 

Yes, I do, but I won't insist on it either.

Thanks,
Guenter