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From: David Laight <David.Laight@ACULAB.COM>
To: 'Guru Das Srinagesh' <gurus@codeaurora.org>,
	"linux-pwm@vger.kernel.org" <linux-pwm@vger.kernel.org>
Cc: "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>,
	"Michael Turquette" <mturquette@baylibre.com>,
	"Stephen Boyd" <sboyd@kernel.org>,
	"linux-clk@vger.kernel.org" <linux-clk@vger.kernel.org>
Subject: RE: [PATCH v8 01/12] clk: pwm: Use 64-bit division function
Date: Wed, 11 Mar 2020 16:58:24 +0000	[thread overview]
Message-ID: <7506bc2972324fd286dac6327ec73a3a@AcuMS.aculab.com> (raw)
In-Reply-To: <338966686a673c241905716c90049993e7bb7d6a.1583889178.git.gurus@codeaurora.org>

From: Guru Das Srinagesh
> Sent: 11 March 2020 01:41
> 
> Since the PWM framework is switching struct pwm_args.period's datatype
> to u64, prepare for this transition by using div64_u64 to handle a
> 64-bit divisor.
> 
> Cc: Michael Turquette <mturquette@baylibre.com>
> Cc: Stephen Boyd <sboyd@kernel.org>
> Cc: linux-clk@vger.kernel.org
> 
> Signed-off-by: Guru Das Srinagesh <gurus@codeaurora.org>
> ---
>  drivers/clk/clk-pwm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/clk/clk-pwm.c b/drivers/clk/clk-pwm.c
> index 87fe0b0e..7b1f7a0 100644
> --- a/drivers/clk/clk-pwm.c
> +++ b/drivers/clk/clk-pwm.c
> @@ -89,7 +89,7 @@ static int clk_pwm_probe(struct platform_device *pdev)
>  	}
> 
>  	if (of_property_read_u32(node, "clock-frequency", &clk_pwm->fixed_rate))
> -		clk_pwm->fixed_rate = NSEC_PER_SEC / pargs.period;
> +		clk_pwm->fixed_rate = div64_u64(NSEC_PER_SEC, pargs.period);

That cannot be needed, a 32 bit division is fine.
More interesting would be whether pargs.period is sane (eg not zero).
I'd assign pargs.period to an 'unsigned int' variable
prior to the division (I hate casts - been bitten by them in the past.).

> 
>  	if (pargs.period != NSEC_PER_SEC / clk_pwm->fixed_rate &&
>  	    pargs.period != DIV_ROUND_UP(NSEC_PER_SEC, clk_pwm->fixed_rate)) {
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)


  reply	other threads:[~2020-03-11 16:58 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <cover.1583889178.git.gurus@codeaurora.org>
2020-03-11  1:41 ` Guru Das Srinagesh
2020-03-11 16:58   ` David Laight [this message]
2020-03-12  2:09     ` Guru Das Srinagesh
2020-03-12  9:14       ` David Laight
2020-03-12 19:09         ` Guru Das Srinagesh
2020-03-19 20:53           ` Guru Das Srinagesh
2020-04-09  2:40         ` Guru Das Srinagesh
2020-03-11  1:41 ` [PATCH v8 02/12] drm/i915: Use 64-bit division macro Guru Das Srinagesh
2020-03-11  1:41 ` [PATCH v8 03/12] hwmon: pwm-fan: " Guru Das Srinagesh
2020-03-11 15:08   ` Guenter Roeck
2020-03-11  1:41 ` [PATCH v8 04/12] ir-rx51: " Guru Das Srinagesh
2020-03-11  2:11   ` Sean Young
2020-03-11  1:41 ` [PATCH v8 05/12] pwm: clps711x: " Guru Das Srinagesh
2020-03-11  1:41 ` [PATCH v8 06/12] pwm: pwm-imx-tpm: " Guru Das Srinagesh
2020-03-11  1:41 ` [PATCH v8 07/12] pwm: imx27: Use 64-bit division macro and function Guru Das Srinagesh
2020-03-11  1:41 ` [PATCH v8 08/12] pwm: sifive: Use 64-bit division macro Guru Das Srinagesh
2020-03-11  1:41 ` [PATCH v8 09/12] pwm: stm32-lp: Use %llu format specifier for period Guru Das Srinagesh
2020-03-11  1:41 ` [PATCH v8 10/12] pwm: sun4i: Use 64-bit division function Guru Das Srinagesh
2020-03-11  3:35   ` Chen-Yu Tsai
2020-03-11  1:41 ` [PATCH v8 11/12] backlight: pwm_bl: " Guru Das Srinagesh
2020-03-11 10:05   ` Daniel Thompson
2020-03-11  1:41 ` [PATCH v8 12/12] pwm: core: Convert period and duty cycle to u64 Guru Das Srinagesh

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