[PATCH][next] power: supply: 88pm860x: make fsm_state array static const, simplify usage

[PATCH][next] power: supply: 88pm860x: make fsm_state array static const, simplify usage

[Colin Ian King]

Don't populate the read-only array fsm_state on the stack at run time,
instead make it static const, this reduces the object code size as
the data is placed on the data segment and this removes the need to
have code to set the array up on each call.

Note that making the size of the strings to a more optimal 11 bytes long
does not seem to reduce the overall size. Making the array an array of
pointers to the strings increases the code size due to the dereferencing
overhead.

Simplify the array access with &fsm_state[info->state][0] with the simpler
expression fsm_state[info->state] to clean up the code.

Original:
   text    data     bss     dec     hex filename
  22884    8272      64   31220    79f4 drivers/power/supply/88pm860x_charger.o

Patched:
   text	   data	    bss	    dec	    hex	filename
  22695	   8368	     64	  31127	   7997	drivers/power/supply/88pm860x_charger.o

Difference:
   text	   data	    bss	    dec
  -189     +96        0     -93

Reduction of 93 bytes total.

gcc version 14.2.0 (x86-64)

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
---
 drivers/power/supply/88pm860x_charger.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/power/supply/88pm860x_charger.c b/drivers/power/supply/88pm860x_charger.c
index 2b9fcb7e71d7..8d99c6ff72ed 100644
--- a/drivers/power/supply/88pm860x_charger.c
+++ b/drivers/power/supply/88pm860x_charger.c
@@ -284,8 +284,8 @@ static int set_charging_fsm(struct pm860x_charger_info *info)
 {
 	struct power_supply *psy;
 	union power_supply_propval data;
-	unsigned char fsm_state[][16] = { "init", "discharge", "precharge",
-		"fastcharge",
+	static const unsigned char fsm_state[][16] = {
+		"init", "discharge", "precharge", "fastcharge",
 	};
 	int ret;
 	int vbatt;
@@ -313,7 +313,7 @@ static int set_charging_fsm(struct pm860x_charger_info *info)
 
 	dev_dbg(info->dev, "Entering FSM:%s, Charger:%s, Battery:%s, "
 		"Allowed:%d\n",
-		&fsm_state[info->state][0],
+		fsm_state[info->state],
 		(info->online) ? "online" : "N/A",
 		(info->present) ? "present" : "N/A", info->allowed);
 	dev_dbg(info->dev, "set_charging_fsm:vbatt:%d(mV)\n", vbatt);
@@ -385,7 +385,7 @@ static int set_charging_fsm(struct pm860x_charger_info *info)
 	}
 	dev_dbg(info->dev,
 		"Out FSM:%s, Charger:%s, Battery:%s, Allowed:%d\n",
-		&fsm_state[info->state][0],
+		fsm_state[info->state],
 		(info->online) ? "online" : "N/A",
 		(info->present) ? "present" : "N/A", info->allowed);
 	mutex_unlock(&info->lock);
-- 
2.50.1

Re: [PATCH][next] power: supply: 88pm860x: make fsm_state array static const, simplify usage

[Sebastian Reichel]

On Thu, 07 Aug 2025 13:13:49 +0100, Colin Ian King wrote:
> Don't populate the read-only array fsm_state on the stack at run time,
> instead make it static const, this reduces the object code size as
> the data is placed on the data segment and this removes the need to
> have code to set the array up on each call.
> 
> Note that making the size of the strings to a more optimal 11 bytes long
> does not seem to reduce the overall size. Making the array an array of
> pointers to the strings increases the code size due to the dereferencing
> overhead.
> 
> [...]

Applied, thanks!

[1/1] power: supply: 88pm860x: make fsm_state array static const, simplify usage
      commit: cb03556acf83b235dfb2e9f86e14f5e5b8a5f1e7

Best regards,
-- 
Sebastian Reichel <sebastian.reichel@collabora.com>