[PATCH] tty: serial: cpm_uart: Fix behaviour for non existing GPIOs

[Christophe Leroy]

devm_gpiod_get_index() doesn't return NULL but -ENOENT when the
requested GPIO doesn't exist,  leading to the following messages:

[    2.742468] gpiod_direction_input: invalid GPIO (errorpointer)
[    2.748147] can't set direction for gpio #2: -2
[    2.753081] gpiod_direction_input: invalid GPIO (errorpointer)
[    2.758724] can't set direction for gpio #3: -2
[    2.763666] gpiod_direction_output: invalid GPIO (errorpointer)
[    2.769394] can't set direction for gpio #4: -2
[    2.774341] gpiod_direction_input: invalid GPIO (errorpointer)
[    2.779981] can't set direction for gpio #5: -2
[    2.784545] ff000a20.serial: ttyCPM1 at MMIO 0xfff00a20 (irq = 39, base_baud = 8250000) is a CPM UART

Use IS_ERR_OR_NULL() to properly check gpiod validity.

Fixes: 97cbaf2c829b ("tty: serial: cpm_uart: Convert to use GPIO descriptors")
Cc: stable@xxxxxxxxxxxxxxx
Cc: Linus Walleij <linus.walleij@xxxxxxxxxx>
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
 drivers/tty/serial/cpm_uart/cpm_uart_core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/serial/cpm_uart/cpm_uart_core.c b/drivers/tty/serial/cpm_uart/cpm_uart_core.c
index a04f74d2e854..3cbe24802296 100644
--- a/drivers/tty/serial/cpm_uart/cpm_uart_core.c
+++ b/drivers/tty/serial/cpm_uart/cpm_uart_core.c
@@ -1217,7 +1217,7 @@ static int cpm_uart_init_port(struct device_node *np,
 
 		gpiod = devm_gpiod_get_index(dev, NULL, i, GPIOD_ASIS);
 
-		if (gpiod) {
+		if (!IS_ERR_OR_NULL(gpiod)) {
 			if (i == GPIO_RTS || i == GPIO_DTR)
 				ret = gpiod_direction_output(gpiod, 0);
 			else
-- 
2.25.0