From 0c727a42043f79db210cdde0366f9137b9c6bf5a Mon Sep 17 00:00:00 2001 From: Fabio Estevam Date: Tue, 18 Aug 2015 12:43:12 -0300 Subject: [PATCH] Revert "serial: imx: remove unbalanced clk_prepare" This reverts commit 9e7b399d6528eac33a6fbfceb2b92af209c3454d. Commit ("9e7b399d6528ea") causes the following warning and sometimes also hangs the system: ------------[ cut here ]------------ WARNING: CPU: 0 PID: 0 at kernel/locking/mutex.c:868 mutex_trylock+0x20c/0x22c() DEBUG_LOCKS_WARN_ON(in_interrupt()) Modules linked in: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.2.0-rc7-next-20150818-00001-g14418a6 #4 Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree) Backtrace: [<80012f08>] (dump_backtrace) from [<800130a4>] (show_stack+0x18/0x1c) r6:00000364 r5:00000000 r4:00000000 r3:00000000 [<8001308c>] (show_stack) from [<807902b8>] (dump_stack+0x88/0xa4) [<80790230>] (dump_stack) from [<8002a604>] (warn_slowpath_common+0x80/0xbc) r5:807945c4 r4:80ab3b50 [<8002a584>] (warn_slowpath_common) from [<8002a6e4>] (warn_slowpath_fmt+0x38/0x40) r8:00000000 r7:8131100c r6:8054c3cc r5:8131300c r4:80b0a570 [<8002a6b0>] (warn_slowpath_fmt) from [<807945c4>] (mutex_trylock+0x20c/0x22c) r3:8095d0d8 r2:8095ab28 [<807943b8>] (mutex_trylock) from [<8054c3cc>] (clk_prepare_lock+0x14/0xf4) r7:8131100c r6:be3f0c80 r5:00000037 r4:be3f0c80 [<8054c3b8>] (clk_prepare_lock) from [<8054dbfc>] (clk_prepare+0x18/0x30) r5:00000037 r4:be3f0c80 [<8054dbe4>] (clk_prepare) from [<8036a600>] (imx_console_write+0x30/0x244) r4:812d0bc8 r3:8132b9a4 To reproduce the problem we only need to let the board idle for something like 30 seconds. Tested on a imx6q-sabresd. Signed-off-by: Fabio Estevam Reviewed-by: Eduardo Valentin Signed-off-by: Greg Kroah-Hartman --- 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; -- 2.7.4