linux-kernel - Re: [PATCH] drm/amdgpu/display: make various arrays static, makes object smaller

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Message-ID: <9579bfae-1db5-d282-79ea-df1966f4c123@amd.com>
Date:   Tue, 8 Oct 2019 13:56:00 +0000
From:   Harry Wentland <hwentlan@....com>
To:     Colin King <colin.king@...onical.com>,
        "Wentland, Harry" <Harry.Wentland@....com>,
        "Li, Sun peng (Leo)" <Sunpeng.Li@....com>,
        "Deucher, Alexander" <Alexander.Deucher@....com>,
        "Koenig, Christian" <Christian.Koenig@....com>,
        "Zhou, David(ChunMing)" <David1.Zhou@....com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        "amd-gfx@...ts.freedesktop.org" <amd-gfx@...ts.freedesktop.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>
CC:     "kernel-janitors@...r.kernel.org" <kernel-janitors@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/amdgpu/display: make various arrays static, makes
 object smaller

On 2019-10-07 5:58 p.m., Colin King wrote:
> From: Colin Ian King <colin.king@...onical.com>
> 
> Don't populate the arrays on the stack but instead make them
> static. Makes the object code smaller by 158 bytes.
> 
> Before:
>    text	   data	    bss	    dec	    hex	filename
>   32468	   2072	      0	  34540	   86ec	display/dc/bios/bios_parser.o
>   22198	   1088	      0	  23286	   5af6	display/dc/bios/bios_parser2.o
>   22278	   1076	      0	  23354	   5b3a	display/dc/dce/dce_mem_input.o
> 
> 81180
> After:
>    text	   data	    bss	    dec	    hex	filename
>   32341	   2136	      0	  34477	   86ad	display/dc/bios/bios_parser.o
>   22070	   1184	      0	  23254	   5ad6	display/dc/bios/bios_parser2.o
>   22119	   1172	      0	  23291	   5afb	display/dc/dce/dce_mem_input.o
> 
> (gcc version 9.2.1, amd64)
> 
> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> ---
>  drivers/gpu/drm/amd/display/dc/bios/bios_parser.c  | 2 +-
>  drivers/gpu/drm/amd/display/dc/bios/bios_parser2.c | 2 +-
>  drivers/gpu/drm/amd/display/dc/dce/dce_mem_input.c | 2 +-
>  3 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/dc/bios/bios_parser.c b/drivers/gpu/drm/amd/display/dc/bios/bios_parser.c
> index 221e0f56389f..65ab225cf542 100644
> --- a/drivers/gpu/drm/amd/display/dc/bios/bios_parser.c
> +++ b/drivers/gpu/drm/amd/display/dc/bios/bios_parser.c
> @@ -2745,7 +2745,7 @@ static enum bp_result bios_get_board_layout_info(
>  	struct bios_parser *bp;
>  	enum bp_result record_result;
>  
> -	const unsigned int slot_index_to_vbios_id[MAX_BOARD_SLOTS] = {
> +	static const unsigned int slot_index_to_vbios_id[MAX_BOARD_SLOTS] = {

Won't this break the multi-GPU case where you'll have multiple driver
instances with different layout?

Harry

>  		GENERICOBJECT_BRACKET_LAYOUT_ENUM_ID1,
>  		GENERICOBJECT_BRACKET_LAYOUT_ENUM_ID2,
>  		0, 0
> diff --git a/drivers/gpu/drm/amd/display/dc/bios/bios_parser2.c b/drivers/gpu/drm/amd/display/dc/bios/bios_parser2.c
> index dff65c0fe82f..809c4a89b899 100644
> --- a/drivers/gpu/drm/amd/display/dc/bios/bios_parser2.c
> +++ b/drivers/gpu/drm/amd/display/dc/bios/bios_parser2.c
> @@ -1832,7 +1832,7 @@ static enum bp_result bios_get_board_layout_info(
>  	struct bios_parser *bp;
>  	enum bp_result record_result;
>  
> -	const unsigned int slot_index_to_vbios_id[MAX_BOARD_SLOTS] = {
> +	static const unsigned int slot_index_to_vbios_id[MAX_BOARD_SLOTS] = {
>  		GENERICOBJECT_BRACKET_LAYOUT_ENUM_ID1,
>  		GENERICOBJECT_BRACKET_LAYOUT_ENUM_ID2,
>  		0, 0
> diff --git a/drivers/gpu/drm/amd/display/dc/dce/dce_mem_input.c b/drivers/gpu/drm/amd/display/dc/dce/dce_mem_input.c
> index 8aa937f496c4..ed0031d5e021 100644
> --- a/drivers/gpu/drm/amd/display/dc/dce/dce_mem_input.c
> +++ b/drivers/gpu/drm/amd/display/dc/dce/dce_mem_input.c
> @@ -395,7 +395,7 @@ static void program_size_and_rotation(
>  {
>  	const struct rect *in_rect = &plane_size->surface_size;
>  	struct rect hw_rect = plane_size->surface_size;
> -	const uint32_t rotation_angles[ROTATION_ANGLE_COUNT] = {
> +	static const uint32_t rotation_angles[ROTATION_ANGLE_COUNT] = {
>  			[ROTATION_ANGLE_0] = 0,
>  			[ROTATION_ANGLE_90] = 1,
>  			[ROTATION_ANGLE_180] = 2,
>