Re: [PATCH] drm/bridge/tc358767: make the array ext_div static const, makes object smaller

[Sam Ravnborg <sam@ravnborg.org>]

Hi Colin,

On Thu, Aug 19, 2021 at 02:38:39PM +0100, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> Don't populate the array ext_div on the stack but instead it
> static const. Makes the object code smaller by 118 bytes:
> 
> Before:
>    text    data    bss     dec    hex filename
>   39449   17500    128   57077   def5 ./drivers/gpu/drm/bridge/tc358767.o
> 
> After:
>    text    data    bss     dec    hex filename
>   39235   17596    128   56959   de7f ./drivers/gpu/drm/bridge/tc358767.o
> 
> (gcc version 10.3.0)

IMO a better argument is that this change prevents any accidental
changes and it align with how we define arrays in many other places.
The compiler may produce a smaller binary but that is just a side-effect
in this case.

	Sam

> 
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
>  drivers/gpu/drm/bridge/tc358767.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/bridge/tc358767.c b/drivers/gpu/drm/bridge/tc358767.c
> index 23a6f90b694b..599c23759400 100644
> --- a/drivers/gpu/drm/bridge/tc358767.c
> +++ b/drivers/gpu/drm/bridge/tc358767.c
> @@ -468,7 +468,7 @@ static int tc_pxl_pll_en(struct tc_data *tc, u32 refclk, u32 pixelclock)
>  	int div, best_div = 1;
>  	int mul, best_mul = 1;
>  	int delta, best_delta;
> -	int ext_div[] = {1, 2, 3, 5, 7};
> +	static const int ext_div[] = {1, 2, 3, 5, 7};
>  	int best_pixelclock = 0;
>  	int vco_hi = 0;
>  	u32 pxl_pllparam;
> -- 
> 2.32.0