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Message-ID: <0a2ea4e54d7bfd61b45cc070eee6b62e8da82190.camel@perches.com>
Subject: Re: [PATCH] drm/bridge/tc358767: make the array ext_div static
 const, makes object smaller
From:   Joe Perches <joe@perches.com>
To:     Colin King <colin.king@canonical.com>,
        Andrzej Hajda <a.hajda@samsung.com>,
        Neil Armstrong <narmstrong@baylibre.com>,
        Robert Foss <robert.foss@linaro.org>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        Jonas Karlman <jonas@kwiboo.se>,
        Jernej Skrabec <jernej.skrabec@gmail.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        dri-devel@lists.freedesktop.org
Cc:     kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org
Date:   Thu, 19 Aug 2021 06:51:23 -0700
In-Reply-To: <20210819133839.10745-1-colin.king@canonical.com>
References: <20210819133839.10745-1-colin.king@canonical.com>
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On Thu, 2021-08-19 at 14:38 +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

Why is text smaller and data larger with this change?

> 
> (gcc version 10.3.0)
> 
> 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;