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Subject[PATCH 2/2] pwm-backlight: Add support for pwm-delay-us property
Date
From: huang lin <hl@rock-chips.com>

Some panel backlight (i.e. N116BGE-L41), in their power sequence
specifications, request a delay between PWM signal and the backlight
enable signal, so use the pwm-delay-us property to meet the timing.

Signed-off-by: huang lin <hl@rock-chips.com>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
---
drivers/video/backlight/pwm_bl.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 002f1ce..c5c4ef0 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>
@@ -30,6 +31,7 @@ struct pwm_bl_data {
unsigned int period;
unsigned int lth_brightness;
unsigned int *levels;
+ unsigned int pwm_delay;
bool enabled;
struct regulator *power_supply;
struct gpio_desc *enable_gpio;
@@ -54,10 +56,14 @@ static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness)
if (err < 0)
dev_err(pb->dev, "failed to enable power supply\n");

+ pwm_enable(pb->pwm);
+
+ if (pb->pwm_delay)
+ usleep_range(pb->pwm_delay, pb->pwm_delay + 2000);
+
if (pb->enable_gpio)
gpiod_set_value_cansleep(pb->enable_gpio, 1);

- pwm_enable(pb->pwm);
pb->enabled = true;
}

@@ -66,12 +72,15 @@ static void pwm_backlight_power_off(struct pwm_bl_data *pb)
if (!pb->enabled)
return;

- pwm_config(pb->pwm, 0, pb->period);
- pwm_disable(pb->pwm);
-
if (pb->enable_gpio)
gpiod_set_value_cansleep(pb->enable_gpio, 0);

+ if (pb->pwm_delay)
+ usleep_range(pb->pwm_delay, pb->pwm_delay + 2000);
+
+ pwm_config(pb->pwm, 0, pb->period);
+ pwm_disable(pb->pwm);
+
regulator_disable(pb->power_supply);
pb->enabled = false;
}
@@ -273,6 +282,7 @@ static int pwm_backlight_probe(struct platform_device *pdev)
pb->dev = &pdev->dev;
pb->enabled = false;

+ of_property_read_u32(pdev->dev.of_node, "pwm-delay-us", &pb->pwm_delay);
pb->enable_gpio = devm_gpiod_get_optional(&pdev->dev, "enable",
GPIOD_ASIS);
if (IS_ERR(pb->enable_gpio)) {
--
2.9.3
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