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-ms and pwm-off-delay-ms proprieties to meet
the timings.
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@xxxxxxxxxxxxx>
Acked-by: Pavel Machek <pavel@xxxxxx>
Acked-by: Daniel Thompson <daniel.thompson@xxxxxxxxxx>
Acked-by: Jingoo Han <jingoohan1@xxxxxxxxx>
Acked-by: Thierry Reding <thierry.reding@xxxxxxxxx>
---
Changes since v5:
- Add Acked-by: Thierry Reding <thierry.reding@xxxxxxxxx>
Changes since v4:
- Rebased on top of mainline.
- Added the acks from Pavel Machek, Daniel thompson and Jingoo Han
Changes since v3:
- Use two named members instead of pwm_delay[] (Daniel and Pavel)
- Use msleep instead of usleep_range. (Pavel)
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 | 19 +++++++++++++++++++
include/linux/pwm_backlight.h | 2 ++
2 files changed, 21 insertions(+)
diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 698ec68bcdc9..8e3f1245f5c5 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 +36,8 @@ struct pwm_bl_data {
struct gpio_desc *enable_gpio;
unsigned int scale;
bool legacy;
+ unsigned int post_pwm_on_delay;
+ unsigned int pwm_off_delay;
int (*notify)(struct device *,
int brightness);
void (*notify_after)(struct device *,
@@ -56,6 +59,9 @@ static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness)
pwm_enable(pb->pwm);
+ if (pb->post_pwm_on_delay)
+ msleep(pb->post_pwm_on_delay);
+
if (pb->enable_gpio)
gpiod_set_value_cansleep(pb->enable_gpio, 1);
@@ -70,6 +76,9 @@ 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_off_delay)
+ msleep(pb->pwm_off_delay);
+
pwm_config(pb->pwm, 0, pb->period);
pwm_disable(pb->pwm);
@@ -178,6 +187,14 @@ 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-ms",
+ &data->post_pwm_on_delay);
+ of_property_read_u32(node, "pwm-off-delay-ms", &data->pwm_off_delay);
+
data->enable_gpio = -EINVAL;
return 0;
}
@@ -276,6 +293,8 @@ static int pwm_backlight_probe(struct platform_device *pdev)
pb->exit = data->exit;
pb->dev = &pdev->dev;
pb->enabled = false;
+ pb->post_pwm_on_delay = data->post_pwm_on_delay;
+ pb->pwm_off_delay = data->pwm_off_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 e8afbd71a140..8ea265a022fd 100644
--- a/include/linux/pwm_backlight.h
+++ b/include/linux/pwm_backlight.h
@@ -14,6 +14,8 @@ struct platform_pwm_backlight_data {
unsigned int lth_brightness;
unsigned int pwm_period_ns;
unsigned int *levels;
+ unsigned int post_pwm_on_delay;
+ unsigned int pwm_off_delay;
/* TODO remove once all users are switched to gpiod_* API */
int enable_gpio;
int (*init)(struct device *dev);
--
2.16.2
--
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