Re: [PATCH] drm/stm: fix warning about multiplication in condition

[Joe Perches <joe@perches.com>]

On Tue, 2017-07-25 at 17:40 +0200, Arnd Bergmann wrote:
> gcc-7 complains about multiplying within a condition being
> suspicious:
> 
> drivers/gpu/drm/stm/dw_mipi_dsi-stm.c: In function 'dsi_pll_get_clkout_khz':
> drivers/gpu/drm/stm/dw_mipi_dsi-stm.c:117:10: error: '*' in boolean context, suggest '&&' instead [-Werror=int-in-bool-context]
> 
> The code here is correct, but can be easily rephrased to make
> that more obvious. I also swap out the error handling and the normal
> code path for clarity.

Thanks, the new code does read much better.

> diff --git a/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c b/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c
[]
> @@ -113,11 +113,13 @@ static enum dsi_color dsi_color_from_mipi(enum mipi_dsi_pixel_format fmt)
>  
>  static int dsi_pll_get_clkout_khz(int clkin_khz, int idf, int ndiv, int odf)
>  {
> +	int divisor = idf * odf;
> +
>  	/* prevent from division by 0 */
> -	if (idf * odf)
> -		return DIV_ROUND_CLOSEST(clkin_khz * ndiv, idf * odf);
> +	if (!divisor)
> +		return 0;
>  
> -	return 0;
> +	return DIV_ROUND_CLOSEST(clkin_khz * ndiv, divisor);
>  }
>  
>  static int dsi_pll_get_params(int clkin_khz, int clkout_khz,