serial: omap: fix runtime-pm handling on unbind
PATCH 1/2 serial: omap: fix runtime-pm handling on unbind
An unbalanced and misplaced synchronous put was used to suspend the device on driver unbind, something which with a likewise misplaced pm_runtime_disable leads to external aborts when an open port is being removed.
Unhandled fault: external abort on non-linefetch (0x1028) at 0xfa024010
...
[<c046e760>] (serial_omap_set_mctrl) from [<c046a064>] (uart_update_mctrl+0x50/0x60) [<c046a064>] (uart_update_mctrl) from [<c046a400>] (uart_shutdown+0xbc/0x138) [<c046a400>] (uart_shutdown) from [<c046bd2c>] (uart_hangup+0x94/0x190) [<c046bd2c>] (uart_hangup) from [<c045b760>] (__tty_hangup+0x404/0x41c) [<c045b760>] (__tty_hangup) from [<c045b794>] (tty_vhangup+0x1c/0x20) [<c045b794>] (tty_vhangup) from [<c046ccc8>] (uart_remove_one_port+0xec/0x260) [<c046ccc8>] (uart_remove_one_port) from [<c046ef4c>] (serial_omap_remove+0x40/0x60) [<c046ef4c>] (serial_omap_remove) from [<c04845e8>] (platform_drv_remove+0x34/0x4c)
Fix this up by resuming the device before deregistering the port and by suspending and disabling runtime pm only after the port has been removed.
Also make sure to disable autosuspend before disabling runtime pm so that the usage count is balanced and device actually suspended before returning.
Note that due to a negative autosuspend delay being set in probe, the unbalanced put would actually suspend the device on first driver unbind, while rebinding and again unbinding would result in a negative power.usage_count.
--- drivers/tty/serial/omap-serial.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
drivers/tty/serial/omap-serial.c +5 -1
@@ -1780,9 +1780,13 @@ static int serial_omap_remove(struct platform_device *dev) {struct uart_omap_port *up =platform_get_drvdata (dev); +pm_runtime_get_sync (up->dev); + +uart_remove_one_port (&serial_omap_reg, &up->port); + +pm_runtime_dont_use_autosuspend (up->dev);pm_runtime_put_sync (up->dev);pm_runtime_disable (up->dev); -uart_remove_one_port (&serial_omap_reg, &up->port);pm_qos_remove_request (&up->pm_qos_request);device_init_wakeup (&dev->dev, false);
Signature · 1 line
2.12.2
PATCH 2/2 serial: omap: suspend device on probe errors
Make sure to actually suspend the device before returning after a failed (or deferred) probe.
Note that autosuspend must be disabled before runtime pm is disabled in order to balance the usage count due to a negative autosuspend delay as well as to make the final put suspend the device synchronously.
--- drivers/tty/serial/omap-serial.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
drivers/tty/serial/omap-serial.c +2 -1
@@ -1767,7 +1767,8 @@ static int serial_omap_probe(struct platform_device *pdev)return 0 ; err_add_port: -pm_runtime_put (&pdev->dev); +pm_runtime_dont_use_autosuspend (&pdev->dev); +pm_runtime_put_sync (&pdev->dev);pm_runtime_disable (&pdev->dev);pm_qos_remove_request (&up->pm_qos_request);device_init_wakeup (up->dev, false);
Signature · 1 line
2.12.2
Re: [PATCH 2/2] serial: omap: suspend device on probe errors
Quoted 11 lines · Johan Hovold
Make sure to actually suspend the device before returning after a failed (or deferred) probe.
Note that autosuspend must be disabled before runtime pm is disabled in order to balance the usage count due to a negative autosuspend delay as well as to make the final put suspend the device synchronously.
Fixes 388bc2622680 ("omap-serial: Fix the error handling in the omap_serial probe")Cc Shubhrajyoti D <[email protected]>Cc Tony Lindgren <[email protected]>Signed-off-by Johan Hovold <[email protected]>
Quoted 29 lines · Johan Hovold
An unbalanced and misplaced synchronous put was used to suspend the device on driver unbind, something which with a likewise misplaced
pm_runtime_disableleads to external aborts when an open port is being removed.Unhandled fault: external abort on non-linefetch (
0x1028) at0xfa024010
...
[<c046e760>] (serial_omap_set_mctrl) from [<c046a064>] (uart_update_mctrl+0x50/0x60) [<c046a064>] (uart_update_mctrl) from [<c046a400>] (uart_shutdown+0xbc/0x138) [<c046a400>] (uart_shutdown) from [<c046bd2c>] (uart_hangup+0x94/0x190) [<c046bd2c>] (uart_hangup) from [<c045b760>] (__tty_hangup+0x404/0x41c) [<c045b760>] (__tty_hangup) from [<c045b794>] (tty_vhangup+0x1c/0x20) [<c045b794>] (tty_vhangup) from [<c046ccc8>] (uart_remove_one_port+0xec/0x260) [<c046ccc8>] (uart_remove_one_port) from [<c046ef4c>] (serial_omap_remove+0x40/0x60) [<c046ef4c>] (serial_omap_remove) from [<c04845e8>] (platform_drv_remove+0x34/0x4c)Fix this up by resuming the device before deregistering the port and by suspending and disabling runtime pm only after the port has been removed.
Also make sure to disable autosuspend before disabling runtime pm so that the usage count is balanced and device actually suspended before returning.
Note that due to a negative autosuspend delay being set in probe, the unbalanced put would actually suspend the device on first driver unbind, while rebinding and again unbinding would result in a negative power.usage_count.
Quoted 5 lines
Fixes 7e9c8e7dbf3b ("serial: omap: make sure to suspend device before remove")Cc Felipe Balbi <[email protected]>Cc Santosh Shilimkar <[email protected]>Cc Tony Lindgren <[email protected]>Signed-off-by Johan Hovold <[email protected]>