Commit 00e7e698 authored by Uwe Kleine-König's avatar Uwe Kleine-König Committed by Lee Jones
Browse files

backlight: pwm_bl: Configure pwm only once per backlight toggle 



When the function pwm_backlight_update_status() was called with
brightness > 0, pwm_get_state() was called twice (once directly and once
in compute_duty_cycle). Also pwm_apply_state() was called twice (once in
pwm_backlight_power_on() and once directly).

Optimize this to do both calls only once.

Note that with this affects the order of regulator and PWM setup. It's
not expected to have a relevant effect on hardware. The rationale for
this is that the regulator (and the GPIO) are reasonable to switch in
pwm_backlight_power_on()/pwm_backlight_power_off() but the PWM has
nothing to do with power. (The post_pwm_on_delay and pwm_off_delay are
still there though.)

Signed-off-by: default avatarUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: default avatarDaniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: default avatarLee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20230120120018.161103-2-u.kleine-koenig@pengutronix.de
parent 744fc2da

drivers/video/backlight/pwm_bl.c

+10 −18
Original line number Diff line number Diff line
@@ -40,10 +40,8 @@ struct pwm_bl_data { 


static void pwm_backlight_power_on(struct pwm_bl_data *pb)

{

	struct pwm_state state;

	int err;



	pwm_get_state(pb->pwm, &state);

	if (pb->enabled)

		return;
@@ -51,9 +49,6 @@ static void pwm_backlight_power_on(struct pwm_bl_data *pb) 
	if (err < 0)

		dev_err(pb->dev, "failed to enable power supply\n");



	state.enabled = true;

	pwm_apply_state(pb->pwm, &state);



	if (pb->post_pwm_on_delay)

		msleep(pb->post_pwm_on_delay);
@@ -65,9 +60,6 @@ static void pwm_backlight_power_on(struct pwm_bl_data *pb) 


static void pwm_backlight_power_off(struct pwm_bl_data *pb)

{

	struct pwm_state state;



	pwm_get_state(pb->pwm, &state);

	if (!pb->enabled)

		return;
@@ -77,28 +69,21 @@ static void pwm_backlight_power_off(struct pwm_bl_data *pb) 
	if (pb->pwm_off_delay)

		msleep(pb->pwm_off_delay);



	state.enabled = false;

	state.duty_cycle = 0;

	pwm_apply_state(pb->pwm, &state);



	regulator_disable(pb->power_supply);

	pb->enabled = false;

}



static int compute_duty_cycle(struct pwm_bl_data *pb, int brightness)

static int compute_duty_cycle(struct pwm_bl_data *pb, int brightness, struct pwm_state *state)

{

	unsigned int lth = pb->lth_brightness;

	struct pwm_state state;

	u64 duty_cycle;



	pwm_get_state(pb->pwm, &state);



	if (pb->levels)

		duty_cycle = pb->levels[brightness];

	else

		duty_cycle = brightness;



	duty_cycle *= state.period - lth;

	duty_cycle *= state->period - lth;

	do_div(duty_cycle, pb->scale);



	return duty_cycle + lth;
@@ -115,11 +100,18 @@ static int pwm_backlight_update_status(struct backlight_device *bl) 


	if (brightness > 0) {

		pwm_get_state(pb->pwm, &state);

		state.duty_cycle = compute_duty_cycle(pb, brightness);

		state.duty_cycle = compute_duty_cycle(pb, brightness, &state);

		state.enabled = true;

		pwm_apply_state(pb->pwm, &state);



		pwm_backlight_power_on(pb);

	} else {

		pwm_backlight_power_off(pb);



		pwm_get_state(pb->pwm, &state);

		state.enabled = false;

		state.duty_cycle = 0;

		pwm_apply_state(pb->pwm, &state);

	}



	if (pb->notify_after)