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[2003:e4:1f20:1d00:f22f:74ff:fe1f:3a53]) by smtp.gmail.com with ESMTPSA id bu24-20020a170906a15800b00722e50dab2csm605167ejb.109.2022.11.03.08.13.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Nov 2022 08:13:01 -0700 (PDT) Date: Thu, 3 Nov 2022 16:12:59 +0100 From: Thierry Reding To: Jon Hunter Cc: Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= , linux-pwm@vger.kernel.org, linux-tegra@vger.kernel.org Subject: Re: [PATCH V2 1/2] pwm: tegra: Improve required rate calculation Message-ID: References: <20221028123356.133796-1-jonathanh@nvidia.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="/Uw4l+j+ezP++LUf" Content-Disposition: inline In-Reply-To: <20221028123356.133796-1-jonathanh@nvidia.com> User-Agent: Mutt/2.2.7 (2022-08-07) Precedence: bulk List-ID: X-Mailing-List: linux-tegra@vger.kernel.org --/Uw4l+j+ezP++LUf Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Oct 28, 2022 at 01:33:55PM +0100, Jon Hunter wrote: > For the case where dev_pm_opp_set_rate() is called to set the PWM clock > rate, the requested rate is calculated as ... >=20 > required_clk_rate =3D (NSEC_PER_SEC / period_ns) << PWM_DUTY_WIDTH; >=20 > The above calculation may lead to rounding errors because the > NSEC_PER_SEC is divided by 'period_ns' before applying the > PWM_DUTY_WIDTH multiplication factor. For example, if the period is > 45334ns, the above calculation yields a rate of 5646848Hz instead of > 5646976Hz. Fix this by applying the multiplication factor before > dividing and using the DIV_ROUND_UP macro which yields the expected > result of 5646976Hz. >=20 > Fixes: 1d7796bdb63a ("pwm: tegra: Support dynamic clock frequency configu= ration") > Signed-off-by: Jon Hunter > Reviewed-by: Uwe Kleine-K=C3=B6nig > --- > Changes since V1: > - Dropped extra parenthesis >=20 > drivers/pwm/pwm-tegra.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) Applied, thanks. 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