diff options
Diffstat (limited to 'drivers/video/backlight/pwm_bl.c')
-rw-r--r-- | drivers/video/backlight/pwm_bl.c | 30 |
1 files changed, 22 insertions, 8 deletions
diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c index 0509fecd5715..fb388148d98f 100644 --- a/drivers/video/backlight/pwm_bl.c +++ b/drivers/video/backlight/pwm_bl.c @@ -45,9 +45,11 @@ static void pwm_backlight_power_on(struct pwm_bl_data *pb) if (pb->enabled) return; - err = regulator_enable(pb->power_supply); - if (err < 0) - dev_err(pb->dev, "failed to enable power supply\n"); + if (pb->power_supply) { + err = regulator_enable(pb->power_supply); + if (err < 0) + dev_err(pb->dev, "failed to enable power supply\n"); + } if (pb->post_pwm_on_delay) msleep(pb->post_pwm_on_delay); @@ -69,7 +71,8 @@ static void pwm_backlight_power_off(struct pwm_bl_data *pb) if (pb->pwm_off_delay) msleep(pb->pwm_off_delay); - regulator_disable(pb->power_supply); + if (pb->power_supply) + regulator_disable(pb->power_supply); pb->enabled = false; } @@ -109,8 +112,16 @@ static int pwm_backlight_update_status(struct backlight_device *bl) pwm_backlight_power_off(pb); pwm_get_state(pb->pwm, &state); - state.enabled = false; state.duty_cycle = 0; + /* + * We cannot assume a disabled PWM to drive its output to the + * inactive state. If we have an enable GPIO and/or a regulator + * we assume that this isn't relevant and we can disable the PWM + * to save power. If however there is neither an enable GPIO nor + * a regulator keep the PWM on be sure to get a constant + * inactive output. + */ + state.enabled = !pb->power_supply && !pb->enable_gpio; pwm_apply_state(pb->pwm, &state); } @@ -408,7 +419,7 @@ static int pwm_backlight_initial_power_state(const struct pwm_bl_data *pb) if (pb->enable_gpio && gpiod_get_value_cansleep(pb->enable_gpio) == 0) active = false; - if (!regulator_is_enabled(pb->power_supply)) + if (pb->power_supply && !regulator_is_enabled(pb->power_supply)) active = false; if (!pwm_is_enabled(pb->pwm)) @@ -489,10 +500,13 @@ static int pwm_backlight_probe(struct platform_device *pdev) goto err_alloc; } - pb->power_supply = devm_regulator_get(&pdev->dev, "power"); + pb->power_supply = devm_regulator_get_optional(&pdev->dev, "power"); if (IS_ERR(pb->power_supply)) { ret = PTR_ERR(pb->power_supply); - goto err_alloc; + if (ret == -ENODEV) + pb->power_supply = NULL; + else + goto err_alloc; } pb->pwm = devm_pwm_get(&pdev->dev, NULL); |