From: narmstrong@baylibre•com (Neil Armstrong)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 3/4] pwm: omap-dmtimer: round load and match values rather than truncate
Date: Wed, 3 Feb 2016 11:24:55 +0100 [thread overview]
Message-ID: <56B1D577.6070808@baylibre.com> (raw)
In-Reply-To: <1454128014-22866-4-git-send-email-drivshin.allworx@gmail.com>
On 01/30/2016 05:26 AM, David Rivshin (Allworx) wrote:
> From: David Rivshin <drivshin@allworx•com>
>
> When converting period and duty_cycle from nanoseconds to fclk cycles,
> the error introduced by the integer division can be appreciable, especially
> in the case of slow fclk or short period. Use DIV_ROUND_CLOSEST_ULL() so
> that the error is kept to +/- 0.5 clock cycles.
>
> Fixes: 6604c6556db9 ("pwm: Add PWM driver for OMAP using dual-mode timers")
> Signed-off-by: David Rivshin <drivshin@allworx•com>
OK for me.
Acked-by: Neil Armstrong <narmstrong@baylibre•com>
Thanks !
> ---
> drivers/pwm/pwm-omap-dmtimer.c | 6 +-----
> 1 file changed, 1 insertion(+), 5 deletions(-)
>
> diff --git a/drivers/pwm/pwm-omap-dmtimer.c b/drivers/pwm/pwm-omap-dmtimer.c
> index 103d729..8c9953c 100644
> --- a/drivers/pwm/pwm-omap-dmtimer.c
> +++ b/drivers/pwm/pwm-omap-dmtimer.c
> @@ -49,11 +49,7 @@ to_pwm_omap_dmtimer_chip(struct pwm_chip *chip)
>
> static u32 pwm_omap_dmtimer_get_clock_cycles(unsigned long clk_rate, int ns)
> {
> - u64 c = (u64)clk_rate * ns;
> -
> - do_div(c, NSEC_PER_SEC);
> -
> - return c;
> + return DIV_ROUND_CLOSEST_ULL((u64)clk_rate * ns, NSEC_PER_SEC);
> }
>
> static void pwm_omap_dmtimer_start(struct pwm_omap_dmtimer_chip *omap)
>
next prev parent reply other threads:[~2016-02-03 10:24 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-30 4:26 [PATCH 0/4] pwm: omap-dmtimer: fix period/duty_cycle calculation David Rivshin (Allworx)
2016-01-30 4:26 ` [PATCH 1/4] pwm: omap-dmtimer: fix inaccurate " David Rivshin (Allworx)
2016-02-03 10:23 ` Neil Armstrong
2016-02-15 20:24 ` Adam Ford
2016-03-04 15:17 ` Thierry Reding
2016-01-30 4:26 ` [PATCH 2/4] pwm: omap-dmtimer: add sanity checking for load and match values David Rivshin (Allworx)
2016-02-01 18:35 ` David Rivshin (Allworx)
2016-02-03 10:24 ` Neil Armstrong
2016-01-30 4:26 ` [PATCH 3/4] pwm: omap-dmtimer: round load and match values rather than truncate David Rivshin (Allworx)
2016-02-03 10:24 ` Neil Armstrong [this message]
2016-03-04 15:18 ` Thierry Reding
2016-01-30 4:26 ` [PATCH 4/4] pwm: omap-dmtimer: add dev_dbg() message for effective period and duty cycle David Rivshin (Allworx)
2016-01-30 14:51 ` Neil Armstrong
2016-02-01 18:22 ` David Rivshin (Allworx)
2016-02-01 18:59 ` Tony Lindgren
2016-02-02 16:23 ` Thierry Reding
2016-02-02 23:44 ` David Rivshin (Allworx)
2016-02-03 14:14 ` Thierry Reding
2016-02-05 19:51 ` David Rivshin (Allworx)
2016-02-09 12:49 ` Neil Armstrong
2016-01-30 14:52 ` [PATCH 0/4] pwm: omap-dmtimer: fix period/duty_cycle calculation Neil Armstrong
2016-02-01 20:14 ` David Rivshin (Allworx)
2016-02-27 1:31 ` David Rivshin (Allworx)
2016-03-04 15:19 ` Thierry Reding
2016-03-04 16:27 ` David Rivshin (Allworx)
[not found] ` <CAHCN7xJYi8VCe8ue_QuYmqTEo-8GPSPiwzM2F_631mMUrwajSA@mail.gmail.com>
2016-03-04 20:01 ` David Rivshin (Allworx)
2016-03-04 20:03 ` Adam Ford
2016-03-04 21:18 ` Thierry Reding
2016-03-04 23:20 ` David Rivshin (Allworx)
2016-03-08 23:23 ` Adam Ford
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