From 3d15344e23c554b6c25f8a5ded3a3657a31e9779 Mon Sep 17 00:00:00 2001 From: Amit Singh Tomar Date: Fri, 17 Apr 2020 01:41:57 +0530 Subject: [PATCH] tty: serial: owl: add "much needed" clk_prepare_enable() commit abf42d2f333b21bf8d33b2fbb8a85fa62037ac01 upstream. 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 Cc: stable Link: https://lore.kernel.org/r/1587067917-1400-1-git-send-email-amittomer25@gmail.com Signed-off-by: Greg Kroah-Hartman --- 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 d2d8b3494685..c55c8507713c 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; }