Re: [PATCH] backlight: pwm_bl: Fix GPIO out for unimplemented .get_direction()

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On 24/03/17 16:42, Daniel Thompson wrote:
On 22/03/17 17:21, Geert Uytterhoeven wrote:
Commit 7613c922315e308a ("backlight: pwm_bl: Move the checks for initial
power state to a separate function") not just moved some code, but made
slight changes in semantics.

If a gpiochip doesn't implement the optional .get_direction() callback,
gpiod_get_direction always returns -EINVAL, which is never equal to
GPIOF_DIR_IN, leading to the GPIO not being configured for output.

To avoid this, invert the test and check for not GPIOF_DIR_OUT instead,
like the original code did.

This restores the display on r8a7740/armadillo.

Fixes: 7613c922315e308a ("backlight: pwm_bl: Move the checks for
initial power state to a separate function")
Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>

Acked-by: Daniel Thommpson <daniel.thompson@xxxxxxxxxx>

Actually, it would be better if there only one m...

Acked-by: Daniel Thompson <daniel.thompson@xxxxxxxxxx>


Daniel.



---
 drivers/video/backlight/pwm_bl.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/video/backlight/pwm_bl.c
b/drivers/video/backlight/pwm_bl.c
index d7efcb632f7d9dde..002f1ce22bd02032 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -297,14 +297,15 @@ static int pwm_backlight_probe(struct
platform_device *pdev)
     }

     /*
-     * If the GPIO is configured as input, change the direction to
output
-     * and set the GPIO as active.
+     * If the GPIO is not known to be already configured as output, that
+     * is, if gpiod_get_direction returns either GPIOF_DIR_IN or
-EINVAL,
+     * change the direction to output and set the GPIO as active.
      * Do not force the GPIO to active when it was already output as it
      * could cause backlight flickering or we would enable the
backlight too
      * early. Leave the decision of the initial backlight state for
later.
      */
     if (pb->enable_gpio &&
-        gpiod_get_direction(pb->enable_gpio) == GPIOF_DIR_IN)
+        gpiod_get_direction(pb->enable_gpio) != GPIOF_DIR_OUT)
         gpiod_direction_output(pb->enable_gpio, 1);

     pb->power_supply = devm_regulator_get(&pdev->dev, "power");






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