Re: [PATCH] pwm-backlight: fix the panel power sequence

On Wed, 14 Oct 2015, YH Huang wrote:

Hi all,

If you have any suggestion, please let me know.
Thanks.

Please don't do that.

If you think the patch has fallen through the gaps, please just RESEND
it, like [RESEND vX] $subject.

On Wed, 2015-09-16 at 22:42 +0800, YH Huang wrote:

quoted

In order to match the panel power sequence, disable the enable_gpio
in the probe function. Also, reorder the code in the power_on and
power_off function to match the timing.

Signed-off-by: YH Huang <redacted>
---
 drivers/video/backlight/pwm_bl.c |   15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index eff379b..99eca1e 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c

@@ -54,10 +54,11 @@ 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->enable_gpio)
 		gpiod_set_value(pb->enable_gpio, 1);
 
-	pwm_enable(pb->pwm);
 	pb->enabled = true;
 }
 

@@ -66,12 +67,12 @@ 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(pb->enable_gpio, 0);
 
+	pwm_config(pb->pwm, 0, pb->period);
+	pwm_disable(pb->pwm);
+
 	regulator_disable(pb->power_supply);
 	pb->enabled = false;
 }

@@ -241,8 +242,7 @@ static int pwm_backlight_probe(struct platform_device *pdev)
 	pb->dev = &pdev->dev;
 	pb->enabled = false;
 
-	pb->enable_gpio = devm_gpiod_get_optional(&pdev->dev, "enable",
-						  GPIOD_OUT_HIGH);
+	pb->enable_gpio = devm_gpiod_get_optional(&pdev->dev, "enable");
 	if (IS_ERR(pb->enable_gpio)) {
 		ret = PTR_ERR(pb->enable_gpio);
 		goto err_alloc;

@@ -264,6 +264,9 @@ static int pwm_backlight_probe(struct platform_device *pdev)
 		pb->enable_gpio = gpio_to_desc(data->enable_gpio);
 	}
 
+	if (pb->enable_gpio)
+		gpiod_direction_output(pb->enable_gpio, 0);
+
 	pb->power_supply = devm_regulator_get(&pdev->dev, "power");
 	if (IS_ERR(pb->power_supply)) {
 		ret = PTR_ERR(pb->power_supply);

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
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