2017-09-12 11:45:51

by Colin King

Subject: [PATCH] backlight: s6e63m0: make const arrays static, reduces object code size

From: Colin Ian King <[email protected]>

Don't populate const arrays on the stack, instead make them
static. Makes the object code smaller by nearly 400 bytes:

Before:
text data bss dec hex filename
15164 6336 0 21500 53fc drivers/video/backlight/s6e63m0.o

After:
text data bss dec hex filename
14669 6432 0 21101 526d drivers/video/backlight/s6e63m0.o

Signed-off-by: Colin Ian King <[email protected]>
---
drivers/video/backlight/s6e63m0.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/video/backlight/s6e63m0.c b/drivers/video/backlight/s6e63m0.c
index 3c4a22a3063a..965c660b2f6b 100644
--- a/drivers/video/backlight/s6e63m0.c
+++ b/drivers/video/backlight/s6e63m0.c
@@ -446,7 +446,7 @@ static int s6e63m0_gamma_ctl(struct s6e63m0 *lcd, int gamma)
static int s6e63m0_ldi_init(struct s6e63m0 *lcd)
{
int ret, i;
- const unsigned short *init_seq[] = {
+ static const unsigned short *init_seq[] = {
seq_panel_condition_set,
seq_display_condition_set,
seq_gamma_setting,
@@ -467,7 +467,7 @@ static int s6e63m0_ldi_init(struct s6e63m0 *lcd)
static int s6e63m0_ldi_enable(struct s6e63m0 *lcd)
{
int ret = 0, i;
- const unsigned short *enable_seq[] = {
+ static const unsigned short *enable_seq[] = {
seq_stand_by_off,
seq_display_on,
};
--
2.14.1

2017-09-12 13:12:13

by Daniel Thompson

Subject: Re: [PATCH] backlight: s6e63m0: make const arrays static, reduces object code size

On 12/09/17 12:45, Colin King wrote:
> From: Colin Ian King <[email protected]>
>
> Don't populate const arrays on the stack, instead make them
> static. Makes the object code smaller by nearly 400 bytes:
>
> Before:
> text data bss dec hex filename
> 15164 6336 0 21500 53fc drivers/video/backlight/s6e63m0.o
>
> After:
> text data bss dec hex filename
> 14669 6432 0 21101 526d drivers/video/backlight/s6e63m0.o

For future records, can you record the compiler version, architecture
and optimization level (-O2 or -Os) to the patch header?


> Signed-off-by: Colin Ian King <[email protected]>
> ---
> drivers/video/backlight/s6e63m0.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/video/backlight/s6e63m0.c b/drivers/video/backlight/s6e63m0.c
> index 3c4a22a3063a..965c660b2f6b 100644
> --- a/drivers/video/backlight/s6e63m0.c
> +++ b/drivers/video/backlight/s6e63m0.c
> @@ -446,7 +446,7 @@ static int s6e63m0_gamma_ctl(struct s6e63m0 *lcd, int gamma)
> static int s6e63m0_ldi_init(struct s6e63m0 *lcd)
> {
> int ret, i;
> - const unsigned short *init_seq[] = {
> + static const unsigned short *init_seq[] = {

I'd be inclined to throw in an extra const to help the compile spot any
negligent maintenance in the future:

static const unsigned short * const init_seq[];


> seq_panel_condition_set,
> seq_display_condition_set,
> seq_gamma_setting,
> @@ -467,7 +467,7 @@ static int s6e63m0_ldi_init(struct s6e63m0 *lcd)
> static int s6e63m0_ldi_enable(struct s6e63m0 *lcd)
> {
> int ret = 0, i;
> - const unsigned short *enable_seq[] = {
> + static const unsigned short *enable_seq[] = {
> seq_stand_by_off,
> seq_display_on,
> };
>