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: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Lee Jones <lee@kernel.org> Link: https://lore.kernel.org/r/20230120120018.161103-2-u.kleine-koenig@pengutronix.de
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1 changed files with 10 additions and 18 deletions
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@ -40,10 +40,8 @@ struct pwm_bl_data {
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static void pwm_backlight_power_on(struct pwm_bl_data *pb)
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{
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struct pwm_state state;
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int err;
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pwm_get_state(pb->pwm, &state);
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if (pb->enabled)
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return;
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@ -51,9 +49,6 @@ static void pwm_backlight_power_on(struct pwm_bl_data *pb)
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if (err < 0)
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dev_err(pb->dev, "failed to enable power supply\n");
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state.enabled = true;
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pwm_apply_state(pb->pwm, &state);
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if (pb->post_pwm_on_delay)
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msleep(pb->post_pwm_on_delay);
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@ -65,9 +60,6 @@ static void pwm_backlight_power_on(struct pwm_bl_data *pb)
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static void pwm_backlight_power_off(struct pwm_bl_data *pb)
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{
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struct pwm_state state;
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pwm_get_state(pb->pwm, &state);
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if (!pb->enabled)
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return;
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@ -77,28 +69,21 @@ static void pwm_backlight_power_off(struct pwm_bl_data *pb)
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if (pb->pwm_off_delay)
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msleep(pb->pwm_off_delay);
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state.enabled = false;
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state.duty_cycle = 0;
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pwm_apply_state(pb->pwm, &state);
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regulator_disable(pb->power_supply);
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pb->enabled = false;
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}
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static int compute_duty_cycle(struct pwm_bl_data *pb, int brightness)
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static int compute_duty_cycle(struct pwm_bl_data *pb, int brightness, struct pwm_state *state)
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{
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unsigned int lth = pb->lth_brightness;
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struct pwm_state state;
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u64 duty_cycle;
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pwm_get_state(pb->pwm, &state);
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if (pb->levels)
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duty_cycle = pb->levels[brightness];
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else
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duty_cycle = brightness;
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duty_cycle *= state.period - lth;
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duty_cycle *= state->period - lth;
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do_div(duty_cycle, pb->scale);
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return duty_cycle + lth;
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@ -115,11 +100,18 @@ static int pwm_backlight_update_status(struct backlight_device *bl)
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if (brightness > 0) {
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pwm_get_state(pb->pwm, &state);
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state.duty_cycle = compute_duty_cycle(pb, brightness);
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state.duty_cycle = compute_duty_cycle(pb, brightness, &state);
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state.enabled = true;
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pwm_apply_state(pb->pwm, &state);
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pwm_backlight_power_on(pb);
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} else {
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pwm_backlight_power_off(pb);
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pwm_get_state(pb->pwm, &state);
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state.enabled = false;
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state.duty_cycle = 0;
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pwm_apply_state(pb->pwm, &state);
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}
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if (pb->notify_after)
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