From abf42d2f333b21bf8d33b2fbb8a85fa62037ac01 Mon Sep 17 00:00:00 2001
From: Amit Singh Tomar <amittomer25@gmail.com>
Date: Fri, 17 Apr 2020 01:41:57 +0530
Subject: [PATCH] tty: serial: owl: add "much needed" clk_prepare_enable()
Git-commit: abf42d2f333b21bf8d33b2fbb8a85fa62037ac01
Patch-mainline: v5.7-rc3
References: git-fixes

commit 8ba92cf59335 ("arm64: dts: actions: s700: Add Clock Management Unit")
breaks the UART on Cubieboard7-lite (based on S700 SoC), This is due to the
fact that generic clk routine clk_disable_unused() disables the gate clks,
and that in turns disables OWL UART (but UART driver never enables it). To
prove this theory, Andre suggested to use "clk_ignore_unused" in kernel
commnd line and it worked (Kernel happily lands into RAMFS world :)).

This commit fix this up by adding clk_prepare_enable().

Fixes: 8ba92cf59335 ("arm64: dts: actions: s700: Add Clock Management Unit")
Signed-off-by: Amit Singh Tomar <amittomer25@gmail.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/1587067917-1400-1-git-send-email-amittomer25@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/tty/serial/owl-uart.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/tty/serial/owl-uart.c b/drivers/tty/serial/owl-uart.c
index 42c8cc93b603..c149f8c30007 100644
--- a/drivers/tty/serial/owl-uart.c
+++ b/drivers/tty/serial/owl-uart.c
@@ -680,6 +680,12 @@ static int owl_uart_probe(struct platform_device *pdev)
 		return PTR_ERR(owl_port->clk);
 	}
 
+	ret = clk_prepare_enable(owl_port->clk);
+	if (ret) {
+		dev_err(&pdev->dev, "could not enable clk\n");
+		return ret;
+	}
+
 	owl_port->port.dev = &pdev->dev;
 	owl_port->port.line = pdev->id;
 	owl_port->port.type = PORT_OWL;
@@ -712,6 +718,7 @@ static int owl_uart_remove(struct platform_device *pdev)
 
 	uart_remove_one_port(&owl_uart_driver, &owl_port->port);
 	owl_uart_ports[pdev->id] = NULL;
+	clk_disable_unprepare(owl_port->clk);
 
 	return 0;
 }
-- 
2.16.4