On 03/22/2017 07:21 PM, 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.
The platforms I have tested the gpio drivers do implement the get_direction()
callback and I was not aware of this behaviour.
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+rene...@glider.be>
Reviewed-by: Peter Ujfalusi <peter.ujfal...@ti.com>
---
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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