serial: tegra: Add missing clk_disable_unprepare() in tegra_uart_hw_init()

Add the missing clk_disable_unprepare() before return from
tegra_uart_hw_init() in the error handling path.
When request_irq() fails in tegra_uart_startup(), 'tup->uart_clk'
has been enabled, fix it by adding clk_disable_unprepare().

Fixes: cc9ca4d9 ("serial: tegra: Only print FIFO error message when an error occurs")
Fixes: d781ec21 ("serial: tegra: report clk rate errors")
Signed-off-by: Yi Yang <yiyang13@huawei.com>
Link: https://lore.kernel.org/r/20221126020852.113378-1-yiyang13@huawei.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/serial-tegra.c

@@ -1046,6 +1046,7 @@ static int tegra_uart_hw_init(struct tegra_uart_port *tup)
 	if (tup->cdata->fifo_mode_enable_status) {
 		ret = tegra_uart_wait_fifo_mode_enabled(tup);
 		if (ret < 0) {
+			clk_disable_unprepare(tup->uart_clk);
 			dev_err(tup->uport.dev,
 				"Failed to enable FIFO mode: %d\n", ret);
 			return ret;
@@ -1067,6 +1068,7 @@ static int tegra_uart_hw_init(struct tegra_uart_port *tup)
 	 */
 	ret = tegra_set_baudrate(tup, TEGRA_UART_DEFAULT_BAUD);
 	if (ret < 0) {
+		clk_disable_unprepare(tup->uart_clk);
 		dev_err(tup->uport.dev, "Failed to set baud rate\n");
 		return ret;
 	}
@@ -1226,10 +1228,13 @@ static int tegra_uart_startup(struct uart_port *u)
 				dev_name(u->dev), tup);
 	if (ret < 0) {
 		dev_err(u->dev, "Failed to register ISR for IRQ %d\n", u->irq);
-		goto fail_hw_init;
+		goto fail_request_irq;
 	}
 	return 0;
 
+fail_request_irq:
+	/* tup->uart_clk is already enabled in tegra_uart_hw_init */
+	clk_disable_unprepare(tup->uart_clk);
 fail_hw_init:
 	if (!tup->use_rx_pio)
 		tegra_uart_dma_channel_free(tup, true);