[PATCH v1] Revert "serial: imx: remove unbalanced clk_prepare"

[Robin Gong]

commit 9e7b399d6528 ("serial: imx: remove unbalanced clk_prepare").
Otherwise below warning happen since there are some printk logs in
interrupt.

[   14.868319] udevd[501]: starting version 182
[   16.386107] random: nonblocking pool is initialized
[   16.386123] ------------[ cut here ]------------
[   16.386140] WARNING: CPU: 0 PID: 501 at kernel/locking/mutex.c:868 mutex_trylock+0x210/0x230()
[   16.386146] DEBUG_LOCKS_WARN_ON(in_interrupt())
[   16.386149] Modules linked in:
[   16.386157] CPU: 0 PID: 501 Comm: udevd Not tainted 4.3.0-rc1-00014-gf843df8 #28
[   16.386160] Hardware name: Freescale i.MX6 SoloX (Device Tree)
[   16.386165] Backtrace:
[   16.386182] [<c0013e98>] (dump_backtrace) from [<c0014090>] (show_stack+0x18/0x1c)
[   16.386192]  r6:c0af1840 r5:00000000 r4:00000000 r3:00000000
[   16.386201] [<c0014078>] (show_stack) from [<c02d4af8>] (dump_stack+0x8c/0xa4)
[   16.386216] [<c02d4a6c>] (dump_stack) from [<c002be14>] (warn_slowpath_common+0x80/0xbc)
[   16.386225]  r6:c07b1ccc r5:00000009 r4:edcf5c60 r3:00000001
[   16.386234] [<c002bd94>] (warn_slowpath_common) from [<c002be88>] (warn_slowpath_fmt+0x38/0x40)
[   16.386246]  r8:c0564694 r7:eeb76880 r6:c13323ec r5:00000001 r4:c0976990
[   16.386255] [<c002be54>] (warn_slowpath_fmt) from [<c07b1ccc>] (mutex_trylock+0x210/0x230)
[   16.386261]  r3:c0978f50 r2:c0976990
[   16.386264]  r4:c0b29a70
[   16.386278] [<c07b1abc>] (mutex_trylock) from [<c0564694>] (clk_prepare_lock+0x14/0xf4)
[   16.386289]  r8:c133000c r7:eeb76880 r6:00000037 r5:c12efbc8 r4:eeb76880
[   16.386297] [<c0564680>] (clk_prepare_lock) from [<c0565e04>] (clk_prepare+0x18/0x38)
[   16.386303]  r5:c12efbc8 r4:eeb76880
[   16.386311] [<c0565dec>] (clk_prepare) from [<c0379a90>] (imx_console_write+0x34/0x248)
[   16.386317]  r4:ee999c10 r3:c134a92c
[   16.386329] [<c0379a5c>] (imx_console_write) from [<c007ac74>] (call_console_drivers.constprop.25+0xe0/0x104)
[   16.386342]  r10:c07b938c r9:00000000 r8:c133000c r7:00000037 r6:edcf4000 r5:c12ef6c0
[   16.386345]  r4:c0afef38
[   16.386355] [<c007ab94>] (call_console_drivers.constprop.25) from [<c007be84>] (console_unlock+0x3fc/0x57c)
[   16.386367]  r10:c132fff0 r9:00000100 r8:00000037 r7:00000000 r6:00000005 r5:c12f4df0

Signed-off-by: Robin Gong <b38343@xxxxxxxxxxxxx>
---
 drivers/tty/serial/imx.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index fe3d41c..d0388a0 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -1631,12 +1631,12 @@ imx_console_write(struct console *co, const char *s, unsigned int count)
 	int locked = 1;
 	int retval;
 
-	retval = clk_prepare_enable(sport->clk_per);
+	retval = clk_enable(sport->clk_per);
 	if (retval)
 		return;
-	retval = clk_prepare_enable(sport->clk_ipg);
+	retval = clk_enable(sport->clk_ipg);
 	if (retval) {
-		clk_disable_unprepare(sport->clk_per);
+		clk_disable(sport->clk_per);
 		return;
 	}
 
@@ -1675,8 +1675,8 @@ imx_console_write(struct console *co, const char *s, unsigned int count)
 	if (locked)
 		spin_unlock_irqrestore(&sport->port.lock, flags);
 
-	clk_disable_unprepare(sport->clk_ipg);
-	clk_disable_unprepare(sport->clk_per);
+	clk_disable(sport->clk_ipg);
+	clk_disable(sport->clk_per);
 }
 
 /*
@@ -1777,7 +1777,15 @@ imx_console_setup(struct console *co, char *options)
 
 	retval = uart_set_options(&sport->port, co, baud, parity, bits, flow);
 
-	clk_disable_unprepare(sport->clk_ipg);
+	clk_disable(sport->clk_ipg);
+	if (retval) {
+		clk_unprepare(sport->clk_ipg);
+		goto error_console;
+	}
+
+	retval = clk_prepare(sport->clk_per);
+	if (retval)
+		clk_disable_unprepare(sport->clk_ipg);
 
 error_console:
 	return retval;
-- 
1.9.1

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