linux-kernel - [PATCH] platform: cznic: turris-omnia-mcu: Fix error check in omnia_mcu_register

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Message-ID: <2b10f2e1-82d1-4f33-92c4-e0cb28b9edac@stanley.mountain>
Date: Thu, 5 Sep 2024 16:16:53 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Marek Behún <kabel@...nel.org>
Cc: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>,
	Arnd Bergmann <arnd@...db.de>, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: [PATCH] platform: cznic: turris-omnia-mcu: Fix error check in
 omnia_mcu_register_trng()

The gpiod_to_irq() function never returns zero.  It returns negative
error codes or a positive IRQ number.  Update the checking to check
for negatives.

Fixes: 41bb142a4028 ("platform: cznic: turris-omnia-mcu: Add support for MCU provided TRNG")
Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
---
For more information about the history of IRQ return values see my blog:
https://staticthinking.wordpress.com/2023/08/07/writing-a-check-for-zero-irq-error-codes/
The gpiod_to_irq() function was modified to not return zero in 2016.

 drivers/platform/cznic/turris-omnia-mcu-trng.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/platform/cznic/turris-omnia-mcu-trng.c b/drivers/platform/cznic/turris-omnia-mcu-trng.c
index ad953fb3c37a..9a1d9292dc9a 100644
--- a/drivers/platform/cznic/turris-omnia-mcu-trng.c
+++ b/drivers/platform/cznic/turris-omnia-mcu-trng.c
@@ -70,8 +70,8 @@ int omnia_mcu_register_trng(struct omnia_mcu *mcu)
 
 	irq_idx = omnia_int_to_gpio_idx[__bf_shf(OMNIA_INT_TRNG)];
 	irq = gpiod_to_irq(gpio_device_get_desc(mcu->gc.gpiodev, irq_idx));
-	if (!irq)
-		return dev_err_probe(dev, -ENXIO, "Cannot get TRNG IRQ\n");
+	if (irq < 0)
+		return dev_err_probe(dev, irq, "Cannot get TRNG IRQ\n");
 
 	/*
 	 * If someone else cleared the TRNG interrupt but did not read the
-- 
2.45.2