linux-kernel - Re: [PATCH 1/2] watchdog: s3c2410_wdt: Use Use devm_clk_get[_optional]

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Message-ID: <431a8ae1-54a7-e71a-484d-cab618a2a1c4@roeck-us.net>
Date:   Sat, 4 Mar 2023 14:10:47 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     Alim Akhtar <alim.akhtar@...sung.com>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-watchdog@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
Subject: Re: [PATCH 1/2] watchdog: s3c2410_wdt: Use Use
 devm_clk_get[_optional]_enabled() helpers

On 3/4/23 13:46, Christophe JAILLET wrote:
> Le 04/03/2023 à 17:56, Guenter Roeck a écrit :
>> The devm_clk_get[_optional]_enabled() helpers:
>>      - call devm_clk_get[_optional]()
>>      - call clk_prepare_enable() and register what is needed in order to
>>        call clk_disable_unprepare() when needed, as a managed resource.
>>
>> This simplifies the code and avoids the calls to clk_disable_unprepare().
>>
>> While at it, use dev_err_probe consistently, and use its return value
>> to return the error code.
>>
>> Cc: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
>> Signed-off-by: Guenter Roeck <linux@...ck-us.net>
>> ---
>>   drivers/watchdog/s3c2410_wdt.c | 45 +++++++---------------------------
>>   1 file changed, 9 insertions(+), 36 deletions(-)
>>
>> diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c
>> index 200ba236a72e..a1fcb79b0b7c 100644
>> --- a/drivers/watchdog/s3c2410_wdt.c
>> +++ b/drivers/watchdog/s3c2410_wdt.c
>> @@ -661,35 +661,17 @@ static int s3c2410wdt_probe(struct platform_device *pdev)
>>       if (IS_ERR(wdt->reg_base))
>>           return PTR_ERR(wdt->reg_base);
>> -    wdt->bus_clk = devm_clk_get(dev, "watchdog");
>> -    if (IS_ERR(wdt->bus_clk)) {
>> -        dev_err(dev, "failed to find bus clock\n");
>> -        return PTR_ERR(wdt->bus_clk);
>> -    }
>> -
>> -    ret = clk_prepare_enable(wdt->bus_clk);
>> -    if (ret < 0) {
>> -        dev_err(dev, "failed to enable bus clock\n");
>> -        return ret;
>> -    }
>> +    wdt->bus_clk = devm_clk_get_enabled(dev, "watchdog");
>> +    if (IS_ERR(wdt->bus_clk))
>> +        return dev_err_probe(dev, PTR_ERR(wdt->bus_clk), "failed to get bus clock\n");
>>       /*
>>        * "watchdog_src" clock is optional; if it's not present -- just skip it
>>        * and use "watchdog" clock as both bus and source clock.
>>        */
>> -    wdt->src_clk = devm_clk_get_optional(dev, "watchdog_src");
>> -    if (IS_ERR(wdt->src_clk)) {
>> -        dev_err_probe(dev, PTR_ERR(wdt->src_clk),
>> -                  "failed to get source clock\n");
>> -        ret = PTR_ERR(wdt->src_clk);
>> -        goto err_bus_clk;
>> -    }
>> -
>> -    ret = clk_prepare_enable(wdt->src_clk);
>> -    if (ret) {
>> -        dev_err(dev, "failed to enable source clock\n");
>> -        goto err_bus_clk;
>> -    }
>> +    wdt->src_clk = devm_clk_get_optional_enabled(dev, "watchdog_src");
>> +    if (IS_ERR(wdt->src_clk))
>> +        return dev_err_probe(dev, PTR_ERR(wdt->src_clk), "failed to get source clock\n");
>>       wdt->wdt_device.min_timeout = 1;
>>       wdt->wdt_device.max_timeout = s3c2410wdt_max_timeout(wdt);
>> @@ -710,7 +692,7 @@ static int s3c2410wdt_probe(struct platform_device *pdev)
>>                    S3C2410_WATCHDOG_DEFAULT_TIME);
>>           } else {
>>               dev_err(dev, "failed to use default timeout\n");
>> -            goto err_src_clk;
>> +            return ret;
> 
> Hi,
> 
> Nit: this also could be "return dev_err_probe()"
> 
>>           }
>>       }
>> @@ -718,7 +700,7 @@ static int s3c2410wdt_probe(struct platform_device *pdev)
>>                      pdev->name, pdev);
>>       if (ret != 0) {
>>           dev_err(dev, "failed to install irq (%d)\n", ret);
>> -        goto err_src_clk;
>> +        return ret;
> 
> Nit: this also could be "return dev_err_probe()"
> 

The primary reason to call dev_err_probe() is that the error may be
-EPROBE_DEFER, in which case the error message is suppressed.
That is not the case for those two functions; they never return
-EPROBE_DEFER. Calling dev_err_probe() would give the false impression
that the functions _might_ return -EPROBE_DEFER.

Thanks,
Guenter