[PATCH] drm: rcar-du: Simplify division/shift logic

[Laurent Pinchart]

Hi Geert,

Thank you for the patch.

On Mon, Feb 21, 2022 at 05:26:15PM +0100, Geert Uytterhoeven wrote:
> "a / (1 << b)" == "a >> b".
> 
> No change in generated code.

If there's no change in generated code, isn't the current code more
readable ? :-)

> Signed-off-by: Geert Uytterhoeven <geert+renesas at glider.be>
> ---
>  drivers/gpu/drm/rcar-du/rcar_lvds.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/rcar-du/rcar_lvds.c b/drivers/gpu/drm/rcar-du/rcar_lvds.c
> index 72a272cfc11ee129..30afc1d3482a9670 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_lvds.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_lvds.c
> @@ -229,7 +229,7 @@ static void rcar_lvds_d3_e3_pll_calc(struct rcar_lvds *lvds, struct clk *clk,
>  				 * the PLL, followed by a an optional fixed /7
>  				 * divider.
>  				 */
> -				fout = fvco / (1 << e) / div7;
> +				fout = (fvco >> e) / div7;
>  				div = max(1UL, DIV_ROUND_CLOSEST(fout, target));
>  				diff = abs(fout / div - target);
>  
> @@ -249,7 +249,7 @@ static void rcar_lvds_d3_e3_pll_calc(struct rcar_lvds *lvds, struct clk *clk,
>  	}
>  
>  done:
> -	output = fin * pll->pll_n / pll->pll_m / (1 << pll->pll_e)
> +	output = (fin * pll->pll_n / pll->pll_m >> pll->pll_e)
>  	       / div7 / pll->div;
>  	error = (long)(output - target) * 10000 / (long)target;
>  

-- 
Regards,

Laurent Pinchart