Commit 892c7788 authored Apr 04, 2017 by Geert Uytterhoeven Committed by Daniel Thompson Apr 19, 2017

backlight: pwm_bl: Fix GPIO out for unimplemented .get_direction()



Commit 7613c922 ("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: 7613c922 ("backlight: pwm_bl: Move the checks for initial power state to a separate function")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>

parent 4f7d029b

drivers/video/backlight/pwm_bl.c

+4 −3

Original line number	Diff line number	Diff line
		@@ -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");