From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f48.google.com (mail-wm1-f48.google.com [209.85.128.48]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4ABAC3D61; Sat, 24 Dec 2022 19:30:45 +0000 (UTC) Received: by mail-wm1-f48.google.com with SMTP id ay40so5587284wmb.2; Sat, 24 Dec 2022 11:30:45 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date:from:to :cc:subject:date:message-id:reply-to; bh=mofTUi3driuT1Kc5x++iqfijA+ZbuXFDPh6ffwSeT3U=; b=ECnyAIn4LF/xDizUZxrueyG4ejveMXeG0yUrU2qIMfTH7uMHMr8LCfPaZWWixbyU76 t9yS14da4MpyzXREt7TIBw5BFOEHvMWbLmbT59MHob0t1MIV0uWXoU6J0DtPW7jHf+8O wrDO9VBOLhqfmNXmAO2KyCkDmv2rYGaV8yir8Yw0gR+kXaMPrShyRJw9O3P7LYHg8jeZ lVy/0Irr5CgZ3ohdBCMBfW4nCTt2dW53Hg2EacFCh6owLMBxEXrI0wd9mByW76IKaJE2 MK+IszJOMcM5gZDpvO5fAQFW1fXpElO6XzJiM0m2IZqNidMqSC/ngEoeDbcp1nLybEZg yaLw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=mofTUi3driuT1Kc5x++iqfijA+ZbuXFDPh6ffwSeT3U=; b=QrBE5a9RQHvEDOXvTFLbYrRA2CnQJvw/m5rNogv+68DOA3xs+pflMrT8jXEDeQ859R SRvVKmfUfB5jJMa9ASGeyFiHZGXRkz9awR9+9c5LNTLZPhIyKi6Mly1SF0bh7s/iMaAF /8owyRI8M/FdwI0ORJhWLIXopvdg69IkotfrsUlJ0Vz78v7DALNc0ix0EfsGkWUDd51v /nxUt4C0VmNTiszzKkLhtqDuovrTBGTfapRC06rzseVB6nuW623rSanZG62T4J7uTBdx PhGsuNkoL8S0qu9qpUdRsQnuhqydZxBgzuRis1D5W+mnVJwT5k4luOj3Yc0AuLDqC1S9 Yrfw== X-Gm-Message-State: AFqh2kqtbyIOHnouVK2p5u/EftntzpiNJ5jhoDoIpE/e49I1Btstuciz 3Y7N40VwFXwYF6UornfpaQA= X-Google-Smtp-Source: AMrXdXtjGKOzguoqURnHPzeA9K8hiZkkssjg4+BjvabqjFnsLtb1JwLeRcbswH/6c6GTd6s+6O9C/A== X-Received: by 2002:a05:600c:1e11:b0:3d2:26e1:bd45 with SMTP id ay17-20020a05600c1e1100b003d226e1bd45mr11787321wmb.29.1671910243474; Sat, 24 Dec 2022 11:30:43 -0800 (PST) Received: from localhost ([102.36.222.112]) by smtp.gmail.com with ESMTPSA id n36-20020a05600c3ba400b003b49bd61b19sm14075726wms.15.2022.12.24.11.30.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 24 Dec 2022 11:30:42 -0800 (PST) Date: Sat, 24 Dec 2022 22:30:39 +0300 From: Dan Carpenter To: Andy Shevchenko Cc: oe-kbuild@lists.linux.dev, Qingtao Cao , lkp@intel.com, oe-kbuild-all@lists.linux.dev, linux-kernel@vger.kernel.org, Bartosz Golaszewski Subject: Re: drivers/gpio/gpio-exar.c:52 exar_offset_to_sel_addr() warn: replace divide condition 'pin / 8' with 'pin >= 8' Message-ID: References: <202212181140.EAWl7FKx-lkp@intel.com> <3D147284-AF8C-4414-9BE1-C83032B6C15D@gmail.com> Precedence: bulk X-Mailing-List: oe-kbuild@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <3D147284-AF8C-4414-9BE1-C83032B6C15D@gmail.com> On Sat, Dec 24, 2022 at 05:19:27PM +0100, Andy Shevchenko wrote: > > > Lähetetty iPhonesta > > > Dan Carpenter kirjoitti 23.12.2022 kello 11.54: > > > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master > > head: f9ff5644bcc04221bae56f922122f2b7f5d24d62 > > commit: 5134272f9f3f71d4e1f3aa15cb09321af49b3646 gpio: exar: access MPIO registers on cascaded chips > > config: ia64-randconfig-m031-20221218 > > compiler: ia64-linux-gcc (GCC) 12.1.0 > > > > If you fix the issue, kindly add following tag where applicable > > | Reported-by: kernel test robot > > | Reported-by: Dan Carpenter > > > > smatch warnings: > > drivers/gpio/gpio-exar.c:52 exar_offset_to_sel_addr() warn: replace divide condition 'pin / 8' with 'pin >= 8' > > drivers/gpio/gpio-exar.c:62 exar_offset_to_lvl_addr() warn: replace divide condition 'pin / 8' with 'pin >= 8' > > > > > > I don’t think this is a good advice. If we want to limit that, we need > to check also upper limit. But. The GPIO framework does that. So, > changing / to >= is bogus. How is checking pin / 8 not mathematically equivalent to pin >= 8? I don't understand this code at all. The divide is inscrutable Is it storing something in in the lower 3 bits and something in bit 4? In that case it might be nicer to just check (pin & BIT(4)). regards, dan carpenter > > > > vim +52 drivers/gpio/gpio-exar.c > > > > 696868d0a79c21 Bartosz Golaszewski 2020-09-30 47 static unsigned int > > 696868d0a79c21 Bartosz Golaszewski 2020-09-30 48 exar_offset_to_sel_addr(struct exar_gpio_chip *exar_gpio, unsigned int offset) > > 696868d0a79c21 Bartosz Golaszewski 2020-09-30 49 { > > 5134272f9f3f71 Qingtao Cao 2022-09-02 50 unsigned int pin = exar_gpio->first_pin + (offset % 16); > > 5134272f9f3f71 Qingtao Cao 2022-09-02 51 unsigned int cascaded = offset / 16; > > 5134272f9f3f71 Qingtao Cao 2022-09-02 @52 unsigned int addr = pin / 8 ? EXAR_OFFSET_MPIOSEL_HI : EXAR_OFFSET_MPIOSEL_LO; > > > > Why not change this to pin > 8 instead. Comparisons are faster than > > divide ops. Way more readable too. > > > > 5134272f9f3f71 Qingtao Cao 2022-09-02 53 > > 5134272f9f3f71 Qingtao Cao 2022-09-02 54 return addr + (cascaded ? exar_gpio->cascaded_offset : 0); > > 696868d0a79c21 Bartosz Golaszewski 2020-09-30 55 } > > 696868d0a79c21 Bartosz Golaszewski 2020-09-30 56 > > 696868d0a79c21 Bartosz Golaszewski 2020-09-30 57 static unsigned int > > 696868d0a79c21 Bartosz Golaszewski 2020-09-30 58 exar_offset_to_lvl_addr(struct exar_gpio_chip *exar_gpio, unsigned int offset) > > 696868d0a79c21 Bartosz Golaszewski 2020-09-30 59 { > > 5134272f9f3f71 Qingtao Cao 2022-09-02 60 unsigned int pin = exar_gpio->first_pin + (offset % 16); > > 5134272f9f3f71 Qingtao Cao 2022-09-02 61 unsigned int cascaded = offset / 16; > > 5134272f9f3f71 Qingtao Cao 2022-09-02 @62 unsigned int addr = pin / 8 ? EXAR_OFFSET_MPIOLVL_HI : EXAR_OFFSET_MPIOLVL_LO; > > 5134272f9f3f71 Qingtao Cao 2022-09-02 63 > > 5134272f9f3f71 Qingtao Cao 2022-09-02 64 return addr + (cascaded ? exar_gpio->cascaded_offset : 0); > > 696868d0a79c21 Bartosz Golaszewski 2020-09-30 65 } > > > > -- > > 0-DAY CI Kernel Test Service > > https://01.org/lkp > >