linux-kernel - Re: [PATCH] rtc: sunplus: fix format string for printing resource

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Message-ID: <54f13745-bec5-8777-4212-6f093947f146@infradead.org>
Date:   Tue, 17 Jan 2023 10:24:49 -0800
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Arnd Bergmann <arnd@...nel.org>
Cc:     Vincent Shih <vincent.sunplus@...il.com>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        Arnd Bergmann <arnd@...db.de>, linux-rtc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] rtc: sunplus: fix format string for printing resource



On 1/17/23 09:55, Alexandre Belloni wrote:
> On 17/01/2023 18:24:44+0100, Arnd Bergmann wrote:
>> From: Arnd Bergmann <arnd@...db.de>
>>
>> On 32-bit architectures with 64-bit resource_size_t, sp_rtc_probe()
>> causes a compiler warning:
>>
>> drivers/rtc/rtc-sunplus.c: In function 'sp_rtc_probe':
>> drivers/rtc/rtc-sunplus.c:243:33: error: format '%x' expects argument of type 'unsigned int', but argument 4 has type 'resource_size_t' {aka 'long long unsigned int'} [-Werror=format=]
>>   243 |         dev_dbg(&plat_dev->dev, "res = 0x%x, reg_base = 0x%lx\n",
>>       |                                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>
>> The best way to print a resource is the special %pR format string,
>> and similarly to print a pointer we can use %p and avoid the cast.
>>
> 
> I got this one this morning, which one is more correct? :)
> https://lore.kernel.org/all/20230117054232.24023-1-rdunlap@infradead.org/

I prefer my handling of res->start and Arnd's no-cast handling of reg_base.
IMO using "%pR" prints too much info, but that's more up to the file's author
or maintainer...


How's that?  :)

>> Fixes: fad6cbe9b2b4 ("rtc: Add driver for RTC in Sunplus SP7021")
>> Signed-off-by: Arnd Bergmann <arnd@...db.de>
>> ---
>>  drivers/rtc/rtc-sunplus.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/rtc/rtc-sunplus.c b/drivers/rtc/rtc-sunplus.c
>> index e8e2ab1103fc..4b578e4d44f6 100644
>> --- a/drivers/rtc/rtc-sunplus.c
>> +++ b/drivers/rtc/rtc-sunplus.c
>> @@ -240,8 +240,8 @@ static int sp_rtc_probe(struct platform_device *plat_dev)
>>  	if (IS_ERR(sp_rtc->reg_base))
>>  		return dev_err_probe(&plat_dev->dev, PTR_ERR(sp_rtc->reg_base),
>>  					    "%s devm_ioremap_resource fail\n", RTC_REG_NAME);
>> -	dev_dbg(&plat_dev->dev, "res = 0x%x, reg_base = 0x%lx\n",
>> -		sp_rtc->res->start, (unsigned long)sp_rtc->reg_base);
>> +	dev_dbg(&plat_dev->dev, "res = %pR, reg_base = %p\n",
>> +		sp_rtc->res, sp_rtc->reg_base);
>>  
>>  	sp_rtc->irq = platform_get_irq(plat_dev, 0);
>>  	if (sp_rtc->irq < 0)
>> -- 
>> 2.39.0
>>
> 

-- 
~Randy