[RESEND PATCH v6 1/5] pwm-backlight: enable/disable the PWM before/after LCD enable toggle.

Enric Balletbo i Serra enric.balletbo at collabora.com
Wed Mar 28 10:03:23 PDT 2018

Before this patch the enable signal was set before the PWM signal and
vice-versa on power off. This sequence is wrong, at least, it is on
the different panels datasheets that I checked, so I inverted the sequence
to follow the specs.

For reference the following panels have the mentioned sequence:
  - N133HSE-EA1 (Innolux)
  - N116BGE (Innolux)
  - N156BGE-L21 (Innolux)
  - B101EAN0 (Auo)
  - B101AW03 (Auo)
  - LTN101NT05 (Samsung)
  - CLAA101WA01A (Chunghwa)

Signed-off-by: Enric Balletbo i Serra <enric.balletbo at collabora.com>
Acked-by: Daniel Thompson <daniel.thompson at linaro.org>
Acked-by: Jingoo Han <jingoohan1 at gmail.com>
Acked-by: Thierry Reding <thierry.reding at gmail.com>
Changes since v5:
 - Add Acked-by: Thierry Reding <thierry.reding at gmail.com>
Changes since v4:
 - Rebase on top of mainline.
 - Add the acks from Daniel Thompson and Jingoo Han.
Changes since v3:
 - List the part numbers for the panel checked (Daniel Thompson)
Changes since v2:
 - Add this as a separate patch (Thierry Reding)
Changes since v1:
 - None
 drivers/video/backlight/pwm_bl.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 1c2289ddd555..698ec68bcdc9 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_cansleep(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)
-	pwm_config(pb->pwm, 0, pb->period);
-	pwm_disable(pb->pwm);
 	if (pb->enable_gpio)
 		gpiod_set_value_cansleep(pb->enable_gpio, 0);
+	pwm_config(pb->pwm, 0, pb->period);
+	pwm_disable(pb->pwm);
 	pb->enabled = false;

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