linux-kernel - Re: [PATCH] drm/imx/dcss: fix 64-bit divisions

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Message-ID: <20200911135634.GI6112@intel.com>
Date:   Fri, 11 Sep 2020 16:56:34 +0300
From:   Ville Syrjälä <ville.syrjala@...ux.intel.com>
To:     Laurentiu Palcu <laurentiu.palcu@....nxp.com>
Cc:     Lucas Stach <l.stach@...gutronix.de>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH] drm/imx/dcss: fix 64-bit divisions

On Fri, Sep 11, 2020 at 04:48:27PM +0300, Laurentiu Palcu wrote:
> Use div_s64() for the 64-bit divisions. This would allow the driver to compile
> on 32-bit architectures, if needed.
> 
> Signed-off-by: Laurentiu Palcu <laurentiu.palcu@....nxp.com>
> ---
>  drivers/gpu/drm/imx/dcss/dcss-scaler.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/imx/dcss/dcss-scaler.c b/drivers/gpu/drm/imx/dcss/dcss-scaler.c
> index cd21905de580..7c1e0e461244 100644
> --- a/drivers/gpu/drm/imx/dcss/dcss-scaler.c
> +++ b/drivers/gpu/drm/imx/dcss/dcss-scaler.c
> @@ -134,7 +134,7 @@ static int div_q(int A, int B)
>  	else
>  		temp -= B / 2;
>  
> -	result = (int)(temp / B);
> +	result = (int)(div_s64(temp, B));
>  	return result;
>  }
>  
> @@ -237,7 +237,7 @@ static void dcss_scaler_gaussian_filter(int fc_q, bool use_5_taps,
>  			ll_temp = coef[phase][i];
>  			ll_temp <<= PSC_COEFF_PRECISION;
>  			ll_temp += sum >> 1;
> -			ll_temp /= sum;

That looks like hand rolled DIV_ROUND_CLOSEST_ULL()

> +			ll_temp = div_s64(ll_temp, sum);
>  			coef[phase][i] = (int)ll_temp;
>  		}
>  	}
> -- 
> 2.17.1
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Ville Syrjälä
Intel

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