Fix the undefined usage of the GPIO consumer API after retrieving the
GPIO description with GPIO_ASIS. The API documentation mentions that
GPIO_ASIS won't set a GPIO direction and requires the user to set a
direction before using the GPIO.

This can be confirmed on i.MX6 hardware, where rfkill-gpio is no longer
able to enabled/disable a device, presumably because the GPIO controller
was never configured for the output direction.

Fixes: b2f750c3a80b ("net: rfkill: gpio: prevent value glitch during probe")
Cc: stable@vger.kernel.org
Signed-off-by: Rouven Czerwinski <r.czerwinski@pengutronix.de>
---
v2:
- remove the if clauses, the gpiod_direction_* functions can handle NULL
  gpio descriptors.

 net/rfkill/rfkill-gpio.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/net/rfkill/rfkill-gpio.c b/net/rfkill/rfkill-gpio.c
index 5a81505fba9ac..4e32d659524e0 100644
--- a/net/rfkill/rfkill-gpio.c
+++ b/net/rfkill/rfkill-gpio.c
@@ -126,6 +126,14 @@ static int rfkill_gpio_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
+	ret = gpiod_direction_output(rfkill->reset_gpio, true);
+	if (ret)
+		return ret;
+
+	ret = gpiod_direction_output(rfkill->shutdown_gpio, true);
+	if (ret)
+		return ret;
+
 	rfkill->rfkill_dev = rfkill_alloc(rfkill->name, &pdev->dev,
 					  rfkill->type, &rfkill_gpio_ops,
 					  rfkill);

base-commit: 994d5c58e50e91bb02c7be4a91d5186292a895c8
-- 
2.39.2

On Thu, Dec 07, 2023 at 08:58:36AM +0100, Rouven Czerwinski wrote:
> Fix the undefined usage of the GPIO consumer API after retrieving the
> GPIO description with GPIO_ASIS. The API documentation mentions that
> GPIO_ASIS won't set a GPIO direction and requires the user to set a
> direction before using the GPIO.
> 
> This can be confirmed on i.MX6 hardware, where rfkill-gpio is no longer
> able to enabled/disable a device, presumably because the GPIO controller
> was never configured for the output direction.
> 
> Fixes: b2f750c3a80b ("net: rfkill: gpio: prevent value glitch during probe")
> Cc: stable@vger.kernel.org
> Signed-off-by: Rouven Czerwinski <r.czerwinski@pengutronix.de>

Reviewed-by: Simon Horman <horms@kernel.org>