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From: Arnd Bergmann <arnd@arndb.de>
To: Guru Das Srinagesh <gurus@codeaurora.org>
Cc: "Linux PWM List" <linux-pwm@vger.kernel.org>,
	"Thierry Reding" <thierry.reding@gmail.com>,
	"Uwe Kleine-König" <uwe@kleine-koenig.org>,
	"Subbaraman Narayanamurthy" <subbaram@codeaurora.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Alexander Shiyan" <shc_work@mail.ru>
Subject: Re: [PATCH v9 04/11] pwm: clps711x: Use 64-bit division macro
Date: Tue, 17 Mar 2020 23:22:06 +0100
Message-ID: <CAK8P3a2Hi_AoRC3g7qKth4e_Y1jZrbBDhWUb3YPZm10FWMu-ig@mail.gmail.com> (raw)
In-Reply-To: <587f9ccae68ad7e1ce97fa8da6037292af1a5095.1584473399.git.gurus@codeaurora.org>

On Tue, Mar 17, 2020 at 9:05 PM Guru Das Srinagesh <gurus@codeaurora.org> wrote:
>
> Since the PWM framework is switching struct pwm_args.period's datatype
> to u64, prepare for this transition by using DIV64_U64_ROUND_CLOSEST to
> handle a 64-bit divisor.
>
> Cc: Alexander Shiyan <shc_work@mail.ru>
> Cc: Arnd Bergmann <arnd@arndb.de>
>
> Signed-off-by: Guru Das Srinagesh <gurus@codeaurora.org>
> ---
>  drivers/pwm/pwm-clps711x.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/pwm/pwm-clps711x.c b/drivers/pwm/pwm-clps711x.c
> index 924d39a..ba9500a 100644
> --- a/drivers/pwm/pwm-clps711x.c
> +++ b/drivers/pwm/pwm-clps711x.c
> @@ -43,7 +43,7 @@ static void clps711x_pwm_update_val(struct clps711x_chip *priv, u32 n, u32 v)
>  static unsigned int clps711x_get_duty(struct pwm_device *pwm, unsigned int v)
>  {
>         /* Duty cycle 0..15 max */
> -       return DIV_ROUND_CLOSEST(v * 0xf, pwm->args.period);
> +       return DIV64_U64_ROUND_CLOSEST(v * 0xf, pwm->args.period);
>  }

Is it actually going to exceed U32_MAX? If not, a type cast may be
more appropriate here than the expensive 64-bit division.

       Arnd

  reply index

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <cover.1584473399.git.gurus@codeaurora.org>
2020-03-17 20:05 ` [PATCH v9 01/11] drm/i915: " Guru Das Srinagesh
2020-03-18 19:08   ` Jani Nikula
2020-03-19 19:35     ` Guru Das Srinagesh
2020-03-17 20:05 ` [PATCH v9 02/11] hwmon: pwm-fan: " Guru Das Srinagesh
2020-03-17 20:05 ` [PATCH v9 03/11] ir-rx51: " Guru Das Srinagesh
2020-03-17 20:05 ` [PATCH v9 04/11] pwm: clps711x: " Guru Das Srinagesh
2020-03-17 22:22   ` Arnd Bergmann [this message]
2020-03-17 23:30     ` Guru Das Srinagesh
2020-03-18  9:49       ` Arnd Bergmann
2020-03-18 17:00         ` Guru Das Srinagesh
2020-03-18 19:38           ` Arnd Bergmann
2020-03-19 20:51             ` Guru Das Srinagesh
2020-03-17 20:05 ` [PATCH v9 05/11] pwm: pwm-imx-tpm: " Guru Das Srinagesh
2020-03-17 20:05 ` [PATCH v9 06/11] pwm: imx27: Use 64-bit division macro and function Guru Das Srinagesh
2020-03-17 20:05 ` [PATCH v9 07/11] pwm: sifive: Use 64-bit division macro Guru Das Srinagesh
2020-03-17 20:05 ` [PATCH v9 08/11] pwm: stm32-lp: Use %llu format specifier for period Guru Das Srinagesh
2020-03-17 20:05 ` [PATCH v9 09/11] pwm: sun4i: Use 64-bit division function Guru Das Srinagesh
2020-03-17 20:05 ` [PATCH v9 10/11] backlight: pwm_bl: " Guru Das Srinagesh
2020-03-17 20:05 ` [PATCH v9 11/11] pwm: core: Convert period and duty cycle to u64 Guru Das Srinagesh

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