Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Feedback-ID: i56a14606:Fastmail
User-Agent: Cyrus-JMAP/3.7.0-alpha0-1187-g678636ba0d-fm-20230113.001-g678636ba
Mime-Version: 1.0
Message-Id: <589415b2-ddf2-44e5-bca5-5971f8ab9576@app.fastmail.com>
In-Reply-To: <54f13745-bec5-8777-4212-6f093947f146@infradead.org>
References: <20230117172450.2938962-1-arnd@kernel.org>
 <Y8bhApoC4Bmgtjoq@mail.local>
 <54f13745-bec5-8777-4212-6f093947f146@infradead.org>
Date:   Tue, 17 Jan 2023 20:36:57 +0100
From:   "Arnd Bergmann" <arnd@arndb.de>
To:     "Randy Dunlap" <rdunlap@infradead.org>,
        "Alexandre Belloni" <alexandre.belloni@bootlin.com>,
        "Arnd Bergmann" <arnd@kernel.org>
Cc:     "Vincent Shih" <vincent.sunplus@gmail.com>,
        "Alessandro Zummo" <a.zummo@towertech.it>,
        linux-rtc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] rtc: sunplus: fix format string for printing resource
Content-Type: text/plain
Precedence: bulk

On Tue, Jan 17, 2023, at 19:24, Randy Dunlap wrote:
> On 1/17/23 09:55, Alexandre Belloni wrote:
>> On 17/01/2023 18:24:44+0100, Arnd Bergmann wrote:
>>> From: Arnd Bergmann <arnd@arndb.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/

Both are equally correct, it's just a preference.

> 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...

Right, I could have equally well picked the %pap version, and just
went for brevity in the source. It's only pr_debug(), so very few
users are going to actually see the output.

     Arnd