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From:   Ying Liu <victor.liu@nxp.com>
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Subject: [PATCH v4] backlight: gpio_backlight: Drop output GPIO direction
 check for initial power state
Thread-Topic: [PATCH v4] backlight: gpio_backlight: Drop output GPIO direction
 check for initial power state
Thread-Index: Adm7tcocHnotirQkKUSANe2HiNXlhw==
Date:   Fri, 21 Jul 2023 09:29:03 +0000
Message-ID: <20230721093342.1532531-1-victor.liu@nxp.com>
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If GPIO pin is in input state but backlight is currently off due to
default pull downs, then initial power state is set to FB_BLANK_UNBLANK
in DT boot mode with phandle link and the backlight is effectively
turned on in gpio_backlight_probe(), which is undesirable according to
patch description of commit ec665b756e6f ("backlight: gpio-backlight:
Correct initial power state handling").

Quote:
---8<---
If in DT boot we have phandle link then leave the GPIO in a state which the
bootloader left it and let the user of the backlight to configure it furthe=
r.
---8<---

So, let's drop output GPIO direction check and only check GPIO value to set
the initial power state.

Fixes: 706dc68102bc ("backlight: gpio: Explicitly set the direction of the =
GPIO")
Signed-off-by: Liu Ying <victor.liu@nxp.com>
---
v3->v4:
* Capitalize words 'gpio' in patch description. (Andy)
* Capitalize word 'gpio' in patch title.
* Quote appropriately in patch description. (Andy)

v2->v3:
* Add Fixes tag. (Daniel)

v1->v2:
* Improve patch description. (Daniel, Bartosz, Andy)

 drivers/video/backlight/gpio_backlight.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/video/backlight/gpio_backlight.c b/drivers/video/backl=
ight/gpio_backlight.c
index 6f78d928f054..38c46936fdcd 100644
--- a/drivers/video/backlight/gpio_backlight.c
+++ b/drivers/video/backlight/gpio_backlight.c
@@ -87,8 +87,7 @@ static int gpio_backlight_probe(struct platform_device *p=
dev)
 		/* Not booted with device tree or no phandle link to the node */
 		bl->props.power =3D def_value ? FB_BLANK_UNBLANK
 					    : FB_BLANK_POWERDOWN;
-	else if (gpiod_get_direction(gbl->gpiod) =3D=3D 0 &&
-		 gpiod_get_value_cansleep(gbl->gpiod) =3D=3D 0)
+	else if (gpiod_get_value_cansleep(gbl->gpiod) =3D=3D 0)
 		bl->props.power =3D FB_BLANK_POWERDOWN;
 	else
 		bl->props.power =3D FB_BLANK_UNBLANK;
--=20
2.37.1