linux-kernel - Re: [PATCH v11 10/12] backlight: pwm

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Date:   Fri, 20 Mar 2020 13:31:23 +0000
From:   Lee Jones <lee.jones@...aro.org>
To:     Guru Das Srinagesh <gurus@...eaurora.org>
Cc:     linux-pwm@...r.kernel.org,
        Thierry Reding <thierry.reding@...il.com>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        Subbaraman Narayanamurthy <subbaram@...eaurora.org>,
        linux-kernel@...r.kernel.org,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Jingoo Han <jingoohan1@...il.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        dri-devel@...ts.freedesktop.org, linux-fbdev@...r.kernel.org
Subject: Re: [PATCH v11 10/12] backlight: pwm_bl: Use 64-bit division function

On Thu, 19 Mar 2020, Guru Das Srinagesh wrote:

> Since the PWM framework is switching struct pwm_state.period's datatype
> to u64, prepare for this transition by using div_u64 to handle a 64-bit
> dividend instead of a straight division operation.
> 
> Cc: Lee Jones <lee.jones@...aro.org>
> Cc: Daniel Thompson <daniel.thompson@...aro.org>
> Cc: Jingoo Han <jingoohan1@...il.com>
> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
> Cc: linux-pwm@...r.kernel.org
> Cc: dri-devel@...ts.freedesktop.org
> Cc: linux-fbdev@...r.kernel.org
> 
> Signed-off-by: Guru Das Srinagesh <gurus@...eaurora.org>
> Reviewed-by: Daniel Thompson <daniel.thompson@...aro.org>
> ---
>  drivers/video/backlight/pwm_bl.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)

Can this patch be taken on its own?

> diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
> index efb4efc..3e5dbcf 100644
> --- a/drivers/video/backlight/pwm_bl.c
> +++ b/drivers/video/backlight/pwm_bl.c
> @@ -625,7 +625,8 @@ static int pwm_backlight_probe(struct platform_device *pdev)
>  		pb->scale = data->max_brightness;
>  	}
>  
> -	pb->lth_brightness = data->lth_brightness * (state.period / pb->scale);
> +	pb->lth_brightness = data->lth_brightness * (div_u64(state.period,
> +				pb->scale));
>  
>  	props.type = BACKLIGHT_RAW;
>  	props.max_brightness = data->max_brightness;

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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