Revert "serial: imx: remove unbalanced clk_prepare"

PATCH New Fabio Estevam 4 participants 5 messages Aug 18, 2015 – Sep 28, 2015

Subsystems (2)

Arm i.MX and Layerscape TTY layer and serial drivers

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Fabio Estevam

author

2015-08-18 15:43 UTC #0 lore raw

PATCH 1/1 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 <[email protected]>

---
 drivers/tty/serial/imx.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

drivers/tty/serial/imx.c +14 -6

index fe3d41c..d0388a0 100644
@@ -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;

Signature · 1 line

1.9.1

Eduardo Valentin

2015-08-18 23:33 UTC #1 lore raw

PATCH 1/1 Revert "serial: imx: remove unbalanced clk_prepare"

Quoted 28 lines · Fabio Estevam

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

Quoted 2 lines

To reproduce the problem we only need to let the board idle for something like 30 seconds.

hmmm.. I really did not see this one. Looking at the code looks like we could be atomic in some of the uart console callbacks.

For this one:

Reviewed-by Eduardo Valentin <[email protected]>

Did you try the runtime pm patch on your end?

BR,

Quoted 59 lines

Tested on a imx6q-sabresd.

Signed-off-by Fabio Estevam <[email protected]>

---
 drivers/tty/serial/imx.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

drivers/tty/serial/imx.c +14 -6

index fe3d41c..d0388a0 100644
@@ -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;

Signature · 1 line

1.9.1

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Fabio Estevam

reviewer

2015-08-20 11:13 UTC #2 lore raw

PATCH 1/1 Revert "serial: imx: remove unbalanced clk_prepare"

Quoted 8 lines · Eduardo Valentin

hmmm.. I really did not see this one. Looking at the code looks like we could be atomic in some of the uart console callbacks.
For this one:
Reviewed-by Eduardo Valentin <[email protected]>
Did you try the runtime pm patch on your end?

I have only tested linux-next.

Fabio Estevam

reviewer

2015-09-26 20:14 UTC #3 lore raw

PATCH 1/1 Revert "serial: imx: remove unbalanced clk_prepare"

In reply to Fabio Estevam

Hi Greg,

Quoted 28 lines · Fabio Estevam

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

Quoted 6 lines

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 <[email protected]>

Could you please consider applying this one for 4.3-rc?

Thanks

Lucas Stach

2015-09-28 08:15 UTC #4 lore raw

PATCH 1/1 Revert "serial: imx: remove unbalanced clk_prepare"

Am Samstag, den 26.09.2015, 17:14 -0300 schrieb Fabio Estevam:

Quoted 32 lines

Hi Greg,

Quoted 28 lines · Fabio Estevam

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

Quoted 9 lines

Quoted 6 lines
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 <[email protected]>
Could you please consider applying this one for 4.3-rc?

To put a bit more wight behind this: without this revert i.MX6 with an active serial console boards are not even able to boot into userspace.

Please apply this as a critical fix.

Regards,
Lucas

Signature · 2 lines

Pengutronix e.K.             | Lucas Stach                 |
Industrial Linux Solutions   | http://www.pengutronix.de/  |