[PATCH] pwm-backlight: fix bogus request for GPIO#0 when instantiated from DT

[Lothar WaÃmann]

commit 257462dbf3ed ("pwm-backlight: switch to gpiod interface")
introduced a regression leading to acquiring a bogus GPIO-0 when
configured from DT without an 'enable-gpios' property.
The driver will happily accept the 0 initialized 'enable_gpio' member
of the struct platform_pwm_backlight_data as valid gpio number, and
request this GPIO as enable pin. In case of multiple driver instances,
the second will fail to register with the error message:
pwm-backlight backlight1.23: failed to request GPIO#0: -16

Fix this by setting enable_gpio in the pdata struct to -EINVAL.

Signed-off-by: Lothar WaÃmann <LW@xxxxxxxxxxxxxxxxxxx>
---
 drivers/video/backlight/pwm_bl.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index d7a3d13..e6ef6b4 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -172,7 +172,7 @@ static int pwm_backlight_parse_dt(struct device *dev,
 		data->dft_brightness = value;
 		data->max_brightness--;
 	}
-
+	data->enable_gpio = -EINVAL;
 	return 0;
 }
 
-- 
1.7.10.4

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