From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f41.google.com (mail-pj1-f41.google.com [209.85.216.41]) (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 74331361954 for ; Wed, 22 Jul 2026 16:03:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.41 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784736225; cv=none; b=lOU6ttK6ewD9o8caHPulom1KZKfzAQnMxDiQPnMmw+d07dv0a5Ymuo4KvUuK9Pob9yotr3foWfhY4uIVFzUru8GPAgLns4/delh3q68ju1jlBnmpoHAC/T8+7K1CmOwUckvqYw3Besa+XJSqvBJ5Chtu1i0qLMFj41+/tiZMpxU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784736225; c=relaxed/simple; bh=1otvit2ICqX01VZfuWeoTPRah7RXDLpRfiXbAwprmwA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=sPuK7TNTWkQhsiZZGzQKBmynKO2sEz8vXAMBLszUKVBvlKFG3ssgdmkPqRFRt2NpRckM91frfEVuE8PiangKgTetH7IrQFCdAbc0NfLaeSvTVv6ZVFj+fml5LsbjNQJ/2dBQwnhyFOEhM5kqXxsU1pfu36fdKk3mNUJGkLXpHww= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=G5KFlmQ3; arc=none smtp.client-ip=209.85.216.41 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="G5KFlmQ3" Received: by mail-pj1-f41.google.com with SMTP id 98e67ed59e1d1-3856d6fbcb3so8367433a91.2 for ; Wed, 22 Jul 2026 09:03:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1784736224; x=1785341024; darn=lists.linux.dev; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to:content-type; bh=+nkpUqQJix6KKXMhqyzdYJniOtozme3lGhsWfFwbkPQ=; b=G5KFlmQ3IOw196nhReU+momCCoLmUmeNusNqSzEspspXgpWUDwWxDjHabPK7yzxhbK P3zoE88knv90ufvNIIBVBw1DWOBjIOQwTSMpCzWqSIfyb1sPgnxS3ggpsDeZYay3C7Xy ktYCzbGwqEt7liWrNNIRWzeWeQEV0Qkqh1BYtoojW3GxEHQgRLLHvBFjBjCzJw2mAH5D n7QjH/J85sjC4LqX3Yk6Afkk1MWI/rD7nbxr+jv8Kt3rHfGdJIAdrPX4I4Ptd+tQfU05 CZC2iLVwGWQR4TB+WTlkWXRBGs0IbIUmexldvJlK2/VViC0GBoiS9os2ucokD/K9s9i7 yDXg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1784736224; x=1785341024; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=+nkpUqQJix6KKXMhqyzdYJniOtozme3lGhsWfFwbkPQ=; b=dupBPubSAetORPgutSJKgox+gMoPfywPVKU76GioIQXMs8yc+7+lIqakKFMp15YANR MhEBPCNpyh7UVXn70HaE8nlzLdYplUf4KyBWwM0FI1c7piAbrv7TcG8XmQrLt+VHUAqU gkI0rUGmptrQMfm9hPyfnl71OxVuudk67P5d8Ic116TrZItGzAs4RKcduBpgB8gXG05l Sa7zTzH6/rGZ4giCofAO9YMSsRC25lPo7ocY2T0a49q8jIXkCxoScckxQGSuy9xfe2wv 2rg54Lxv8gGZAjtbyMzwvCOPtIXx8Aj2/tTQ31QbxImBdOOmpdJ+33jOSggFFWQQUtUB ERAg== X-Forwarded-Encrypted: i=1; AHgh+RpPH3fZTgPWDVMVomZLXPqdVVYrt5ZvRyD3CCQqOclPl7Pk37ehgTH/EMzXSq1qSSPdxOZWR5n5ZPcPQW4B@lists.linux.dev X-Gm-Message-State: AOJu0YzTJRuIF++0uAWkCfgX6epXCuLChGFSIdxjoSNArUc1h4ewu+Vr H3CniycaGSpU3bOuusavtYi8Mf1Di1TQa1O/L/jry1FiLgvXOtzaYgn3 X-Gm-Gg: AR+sD12p6ooP1Xc0vqYbuBvXu9wAG/cw3Y/Gk+NWBFgBcOhd8RyDOPAUBEWlo3nRAz9 3srb8J/mz3jqnEBgHXXkm6ChJx3qUJIMvj17RVZc5lMh9Rm4P7gULuTWy9t9UzChQwD6W5GBx0O xczJpEy+CdBPUVnO2L/ooBy4z5jvUARAzxMS2Hsnkm0Sa4P/FAjHyTVvd8DrIg73Us5ezjBtkMQ cQsFPHSTc6ELS0Jd/dnU7bQNqiMri63ZHFuvpId2ekL9+UCk3s/EL+w3Nn9VEXdeAq+WFX+UXlO XH9H309yWZaHnD4lzzwB+XYXYjaL3MGoSI4764wCR4ESb1dI+shzWkSAH8nKITQ62FfKOFrh+ca oz3OSGQSb1fl6ZnGS2OqJ66J1fjs7fPUBr4mFU2MdObiEuLT6aXkHxSgRmeYSIH5zqhuY7I2rhT 8qem5CCjuyPrD1e8GUXDGL4A== X-Received: by 2002:a17:90b:568e:b0:38e:673:5d18 with SMTP id 98e67ed59e1d1-38e4b56a0c2mr21959475a91.36.1784736223565; Wed, 22 Jul 2026 09:03:43 -0700 (PDT) Received: from kernel ([103.219.206.61]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-13d130ce035sm7548395c88.13.2026.07.22.09.03.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 Jul 2026 09:03:42 -0700 (PDT) Date: Wed, 22 Jul 2026 21:33:33 +0530 From: Mohamad Raizudeen To: Joshua Crofts Cc: jic23@kernel.org, dlechner@baylibre.com, andy@kernel.org, nuno.sa@analog.com, gregkh@linuxfoundation.org, skhan@linuxfoundation.org, me@brighamcampbell.com, jkoolstra@xs4all.nl, linux-iio@vger.kernel.org, linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org, Andy Shevchenko Subject: Re: [PATCH v2] staging: iio: frequency: ad9832/ad9834: add comment explaining do_div usage Message-ID: References: <20260630032322.5805-1-raizudeen.kerneldev@gmail.com> <20260722082227.18768-1-raizudeen.kerneldev@gmail.com> <20260722104617.000050fa@gmail.com> Precedence: bulk X-Mailing-List: linux-staging@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260722104617.000050fa@gmail.com> On Wed, Jul 22, 2026 at 10:46:17AM +0200, Joshua Crofts wrote: > On Wed, 22 Jul 2026 13:52:27 +0530 > Mohamad Raizudeen wrote: > > Previous attempts to change do_div() to div64_ul() were rejected because > > mclk will always fit within 32 bits for this hardware, making do_div() > > safe to use. > > > > However, Coccinelle continues to flag this as a false positive. To > > prevent future developers from submitting unnecessary fixes, add a > > comment explaining why do_div() is intentionally kept. > > > > Suggested-by: Andy Shevchenko > > Signed-off-by: Mohamad Raizudeen > > --- > > Please don't send a new version as a reply to the previous version, > as it can break tooling such as b4 for patch review. > > As for the comment, I think it's good, however I'm not sure whether > this should be split into two patches, given that this is a small > change. Andy, what do you think? > > > diff --git a/drivers/staging/iio/frequency/ad9832.c b/drivers/staging/iio/frequency/ad9832.c > > index 60c33e10c46f..6d046e9121e2 100644 > > --- a/drivers/staging/iio/frequency/ad9832.c > > +++ b/drivers/staging/iio/frequency/ad9832.c > > @@ -118,6 +118,13 @@ static unsigned long ad9832_calc_freqreg(unsigned long mclk, unsigned long fout) > > { > > u64 freqreg = (u64)fout << AD9832_FREQ_BITS; > > > > + /* > > + * mclk is an unsigned long, which triggers a Coccinelle false positive > > + * warning about using do_div() for 64-by-32 division. However, mclk > > + * for this hardware will always fit within 32 bits, so do_div() is > > + * safe to use here. > > + */ > > + > > Unnecessary blank line here, you want to couple the comment with the > line that it's describing. > > > do_div(freqreg, mclk); > > return freqreg; > > } > > diff --git a/drivers/staging/iio/frequency/ad9834.c b/drivers/staging/iio/frequency/ad9834.c > > index 33dfd723923c..8722f3a01cde 100644 > > --- a/drivers/staging/iio/frequency/ad9834.c > > +++ b/drivers/staging/iio/frequency/ad9834.c > > @@ -103,6 +103,13 @@ static unsigned int ad9834_calc_freqreg(unsigned long mclk, unsigned long fout) > > { > > unsigned long long freqreg = (u64)fout * (u64)BIT(AD9834_FREQ_BITS); > > > > + /* > > + * mclk is an unsigned long, which triggers a Coccinelle false positive > > + * warning about using do_div() for 64-by-32 division. However, mclk > > + * for this hardware will always fit within 32 bits, so do_div() is > > + * safe to use here. > > + */ > > + > > Ditto. > > > do_div(freqreg, mclk); > > return freqreg; > > } > > > > -- > Kind regards, > Joshua Crofts Hi Joshua, Thanks you for reviewing the patch and for the clarifications. I understood and will make sure v3 is sent as a new and separate email thread without in-reply-to header so i doesn't break b4. Sure, I will remove the unnecessary blank line. I will hold off sending v3 until I hear from Andy regarding whether this should be split into two patches or kept as one. Thanks & regards, Mohamad Raizudeen