[PATCH 4.4 115/190] Fix serial console on SNI RM400 machines

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>


[ Upstream commit e279e6d98e0cf2c2fe008b3c29042b92f0e17b1d ]

sccnxp driver doesn't get the correct uart clock rate, if CONFIG_HAVE_CLOCK
is disabled. Correct usage of clk API to make it work with/without it.

Fixes: 90efa75f7ab0 (serial: sccnxp: Using CLK API for getting UART clock)

Suggested-by: Russell King - ARM Linux <linux@xxxxxxxxxxxxxxx>
Signed-off-by: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/tty/serial/sccnxp.c |   15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

--- a/drivers/tty/serial/sccnxp.c
+++ b/drivers/tty/serial/sccnxp.c
@@ -884,14 +884,19 @@ static int sccnxp_probe(struct platform_
 
 	clk = devm_clk_get(&pdev->dev, NULL);
 	if (IS_ERR(clk)) {
-		if (PTR_ERR(clk) == -EPROBE_DEFER) {
-			ret = -EPROBE_DEFER;
+		ret = PTR_ERR(clk);
+		if (ret == -EPROBE_DEFER)
 			goto err_out;
-		}
+		uartclk = 0;
+	} else {
+		clk_prepare_enable(clk);
+		uartclk = clk_get_rate(clk);
+	}
+
+	if (!uartclk) {
 		dev_notice(&pdev->dev, "Using default clock frequency\n");
 		uartclk = s->chip->freq_std;
-	} else
-		uartclk = clk_get_rate(clk);
+	}
 
 	/* Check input frequency */
 	if ((uartclk < s->chip->freq_min) || (uartclk > s->chip->freq_max)) {