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Wed, 22 Jul 2026 01:22:39 -0700 (PDT) From: Mohamad Raizudeen To: jic23@kernel.org, dlechner@baylibre.com, andy@kernel.org, nuno.sa@analog.com Cc: 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, Mohamad Raizudeen , Andy Shevchenko Subject: [PATCH v2] staging: iio: frequency: ad9832/ad9834: add comment explaining do_div usage Date: Wed, 22 Jul 2026 13:52:27 +0530 Message-ID: <20260722082227.18768-1-raizudeen.kerneldev@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260630032322.5805-1-raizudeen.kerneldev@gmail.com> References: <20260630032322.5805-1-raizudeen.kerneldev@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 --- Changes in v2: - Instead of changing do_div to div64_ul, added a comment explaining why do_div is kept, as requested by Andy Shevchenko and Joshua Crofts. drivers/staging/iio/frequency/ad9832.c | 7 +++++++ drivers/staging/iio/frequency/ad9834.c | 7 +++++++ 2 files changed, 14 insertions(+) diff --git a/drivers/staging/iio/frequency/ad9832.c b/drivers/staging/iio/f= requency/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 =3D (u64)fout << AD9832_FREQ_BITS; =20 + /* + * 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. + */ + do_div(freqreg, mclk); return freqreg; } diff --git a/drivers/staging/iio/frequency/ad9834.c b/drivers/staging/iio/f= requency/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 =3D (u64)fout * (u64)BIT(AD9834_FREQ_BITS); =20 + /* + * 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. + */ + do_div(freqreg, mclk); return freqreg; } --=20 2.53.0