[PATCH tty/serial 1/1] tty: serial: imx: keep console clocks always on

[Fugang Duan <fugang.duan@xxxxxxx>]

For below code, there has chance to cause deadlock in SMP system:
Thread 1:
clk_enable_lock();
pr_info("debug message");
clk_enable_unlock(flags);

Thread 2:
imx_uart_console_write()
	clk_enable()
		clk_enable_lock();

Thread 1:
Acuired clk enable_lock -> printk -> console_trylock_spinning
Thread 2:
console_unlock() -> imx_uart_console_write -> clk_disable -> Acquite clk enable_lock

So the patch is to keep console port clocks always on like
other console drivers.

Signed-off-by: Fugang Duan <fugang.duan@xxxxxxx>
---
 drivers/tty/serial/imx.c | 19 +++----------------
 1 file changed, 3 insertions(+), 16 deletions(-)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 1731d9728865..4d6c009ddc31 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -2004,15 +2004,6 @@ imx_uart_console_write(struct console *co, const char *s, unsigned int count)
 	int locked = 1;
 	int retval;
 
-	retval = clk_enable(sport->clk_per);
-	if (retval)
-		return;
-	retval = clk_enable(sport->clk_ipg);
-	if (retval) {
-		clk_disable(sport->clk_per);
-		return;
-	}
-
 	if (sport->port.sysrq)
 		locked = 0;
 	else if (oops_in_progress)
@@ -2047,9 +2038,6 @@ imx_uart_console_write(struct console *co, const char *s, unsigned int count)
 
 	if (locked)
 		spin_unlock_irqrestore(&sport->port.lock, flags);
-
-	clk_disable(sport->clk_ipg);
-	clk_disable(sport->clk_per);
 }
 
 /*
@@ -2150,15 +2138,14 @@ imx_uart_console_setup(struct console *co, char *options)
 
 	retval = uart_set_options(&sport->port, co, baud, parity, bits, flow);
 
-	clk_disable(sport->clk_ipg);
 	if (retval) {
-		clk_unprepare(sport->clk_ipg);
+		clk_disable_unprepare(sport->clk_ipg);
 		goto error_console;
 	}
 
-	retval = clk_prepare(sport->clk_per);
+	retval = clk_prepare_enable(sport->clk_per);
 	if (retval)
-		clk_unprepare(sport->clk_ipg);
+		clk_disable_unprepare(sport->clk_ipg);
 
 error_console:
 	return retval;
-- 
2.17.1