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Date: Mon, 18 Mar 2024 19:17:27 +0100
From: Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= <u.kleine-koenig@pengutronix.de>
To: Nylon Chen <nylon.chen@sifive.com>
Cc: linux-riscv@lists.infradead.org, devicetree@vger.kernel.org, 
	linux-kernel@vger.kernel.org, linux-pwm@vger.kernel.org, conor@kernel.org, robh+dt@kernel.org, 
	krzysztof.kozlowski+dt@linaro.org, palmer@dabbelt.com, paul.walmsley@sifive.com, 
	aou@eecs.berkeley.edu, thierry.reding@gmail.com, vincent.chen@sifive.com, 
	zong.li@sifive.com, nylon7717@gmail.com
Subject: Re: [PATCH v9 3/3] pwm: sifive: Fix the error in the idempotent test
 within the pwm_apply_state_debug function
Message-ID: <jvwgsszvs4jtcytcphsdjulzgqfqzdp4sisu236ddwsqgmvriw@ngi4ljgh5b74>
References: <20240222081231.213406-1-nylon.chen@sifive.com>
 <20240222081231.213406-4-nylon.chen@sifive.com>
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Hello,

On Thu, Feb 22, 2024 at 04:12:31PM +0800, Nylon Chen wrote:
> Round the result to the nearest whole number. This ensures that
> real_period is always a reasonable integer that is not lower than the
> actual value.
>=20
> e.g.
> $ echo 110 > /sys/devices/platform/led-controller-1/leds/d12/brightness
> $ .apply is not idempotent (ena=3D1 pol=3D0 1739692/4032985) -> (ena=3D1 =
pol=3D0 1739630/4032985)
>=20
> Co-developed-by: Zong Li <zong.li@sifive.com>
> Signed-off-by: Zong Li <zong.li@sifive.com>
> Signed-off-by: Nylon Chen <nylon.chen@sifive.com>
> ---
>  drivers/pwm/pwm-sifive.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>=20
> diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c
> index a586cfe4191b..bebcbebacccd 100644
> --- a/drivers/pwm/pwm-sifive.c
> +++ b/drivers/pwm/pwm-sifive.c
> @@ -101,7 +101,7 @@ static void pwm_sifive_update_clock(struct pwm_sifive=
_ddata *ddata,
> =20
>  	/* As scale <=3D 15 the shift operation cannot overflow. */
>  	num =3D (unsigned long long)NSEC_PER_SEC << (PWM_SIFIVE_CMPWIDTH + scal=
e);
> -	ddata->real_period =3D div64_ul(num, rate);
> +	ddata->real_period =3D DIV_ROUND_UP_ULL(num, rate);
>  	dev_dbg(ddata->chip.dev,
>  		"New real_period =3D %u ns\n", ddata->real_period);
>  }

pwm_sifive_apply has a DIV64_U64_ROUND_CLOSEST(). I wonder if that needs
adaption, too?!

Best regards
Uwe

--=20
Pengutronix e.K.                           | Uwe Kleine-K=F6nig            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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