[PATCH v3 3/5] pwm-backlight: add support for PWM delays proprieties.
From: Enric Balletbo i Serra <hidden>
Date: 2017-07-17 21:28:34
Also in:
linux-pwm, linux-rockchip, lkml
Subsystem:
backlight class/subsystem, framebuffer layer, the rest · Maintainers:
Lee Jones, Daniel Thompson, Jingoo Han, Helge Deller, Linus Torvalds
Some panels (i.e. N116BGE-L41), in their power sequence specifications, request a delay between set the PWM signal and enable the backlight and between clear the PWM signal and disable the backlight. Add support for the new post-pwm-on-delay-us and pwm-off-delay-us proprieties to meet the timings. Signed-off-by: Enric Balletbo i Serra <redacted> --- Changes since v2: - Move the pwm/enable sequence to another patch (Thierry Reding) Changes since v1: - As suggested by Daniel Thompson - Do not assume power-on delay and power-off delay will be the same - Move the check of dt property to the parse dt function. drivers/video/backlight/pwm_bl.c | 17 +++++++++++++++++ include/linux/pwm_backlight.h | 1 + 2 files changed, 18 insertions(+)
diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 909a686..528155d 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c@@ -10,6 +10,7 @@ * published by the Free Software Foundation. */ +#include <linux/delay.h> #include <linux/gpio/consumer.h> #include <linux/gpio.h> #include <linux/module.h>
@@ -35,6 +36,7 @@ struct pwm_bl_data { struct gpio_desc *enable_gpio; unsigned int scale; bool legacy; + unsigned int pwm_delay[2]; int (*notify)(struct device *, int brightness); void (*notify_after)(struct device *,
@@ -56,6 +58,9 @@ static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness) pwm_enable(pb->pwm); + if (pb->pwm_delay[0]) + usleep_range(pb->pwm_delay[0], pb->pwm_delay[0] * 2); + if (pb->enable_gpio) gpiod_set_value_cansleep(pb->enable_gpio, 1);
@@ -70,6 +75,9 @@ static void pwm_backlight_power_off(struct pwm_bl_data *pb) if (pb->enable_gpio) gpiod_set_value_cansleep(pb->enable_gpio, 0); + if (pb->pwm_delay[1]) + usleep_range(pb->pwm_delay[1], pb->pwm_delay[1] * 2); + pwm_config(pb->pwm, 0, pb->period); pwm_disable(pb->pwm);
@@ -175,6 +183,14 @@ static int pwm_backlight_parse_dt(struct device *dev, data->max_brightness--; } + /* + * These values are optional and set as 0 by default, the out values + * are modified only if a valid u32 value can be decoded. + */ + of_property_read_u32(node, "post-pwm-on-delay-us", + &data->pwm_delay[0]); + of_property_read_u32(node, "pwm-off-delay-us", &data->pwm_delay[1]); + data->enable_gpio = -EINVAL; return 0; }
@@ -273,6 +289,7 @@ static int pwm_backlight_probe(struct platform_device *pdev) pb->exit = data->exit; pb->dev = &pdev->dev; pb->enabled = false; + memcpy(pb->pwm_delay, data->pwm_delay, sizeof(pb->pwm_delay)); pb->enable_gpio = devm_gpiod_get_optional(&pdev->dev, "enable", GPIOD_ASIS);
diff --git a/include/linux/pwm_backlight.h b/include/linux/pwm_backlight.h
index efdd922..bf37131 100644
--- a/include/linux/pwm_backlight.h
+++ b/include/linux/pwm_backlight.h@@ -13,6 +13,7 @@ struct platform_pwm_backlight_data { unsigned int lth_brightness; unsigned int pwm_period_ns; unsigned int *levels; + unsigned int pwm_delay[2]; /* TODO remove once all users are switched to gpiod_* API */ int enable_gpio; int (*init)(struct device *dev);
--
2.9.3