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

From: Ville Syrjälä
Date: Fri Sep 11 2020 - 12:33:01 EST


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@xxxxxxxxxxx>
> ---
> 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
>
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--
Ville Syrjälä
Intel