[PATCH v4] serial: mps2-uart: Check for error irq

[Jiasheng Jiang]

For the possible failure of the platform_get_irq(), the returned irq
could be error number and will finally cause the failure of the
request_irq().
Consider that platform_get_irq() can now in certain cases 
return -EPROBE_DEFER, and the consequences of letting request_irq() 
effectively convert that into -EINVAL, even at probe time rather than 
later on.
So it might be better to check just now.

Fixes: 041f031def33 ("serial: mps2-uart: add MPS2 UART driver")
Signed-off-by: Jiasheng Jiang <jiasheng@xxxxxxxxxxx>
---
Changelog:

v3 -> v4

*Change 1. Using error variable to check.
*Change 2. Add new commit message.
*Change 3. Refine the commit message to be more reasonable.
---
 drivers/tty/serial/mps2-uart.c | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/mps2-uart.c b/drivers/tty/serial/mps2-uart.c
index 587b42f754cb..24a52300d8d9 100644
--- a/drivers/tty/serial/mps2-uart.c
+++ b/drivers/tty/serial/mps2-uart.c
@@ -584,11 +584,29 @@ static int mps2_init_port(struct platform_device *pdev,
 
 
 	if (mps_port->flags & UART_PORT_COMBINED_IRQ) {
-		mps_port->port.irq = platform_get_irq(pdev, 0);
+		ret = platform_get_irq(pdev, 0);
+		if (ret < 0)
+			return ret;
+
+		mps_port->port.irq = ret;
 	} else {
-		mps_port->rx_irq = platform_get_irq(pdev, 0);
-		mps_port->tx_irq = platform_get_irq(pdev, 1);
-		mps_port->port.irq = platform_get_irq(pdev, 2);
+		ret = platform_get_irq(pdev, 0);
+		if (ret < 0)
+			return ret;
+
+		mps_port->rx_irq = ret;
+
+		ret = platform_get_irq(pdev, 1);
+		if (ret < 0)
+			return ret;
+
+		mps_port->tx_irq = ret;
+
+		ret = platform_get_irq(pdev, 2);
+		if (ret < 0)
+			return ret;
+
+		mps_port->port.irq = ret;
 	}
 
 	return ret;
-- 
2.25.1