From: Shawn Guo shawn.guo@linaro.org
[ Upstream commit 4561d8008a467cb05ac632a215391d6b787f40aa ]
The following warning is seen with non-console UART instance when system hibernates.
[ 37.371969] ------------[ cut here ]------------ [ 37.376599] uart3_root_clk already disabled [ 37.380810] WARNING: CPU: 0 PID: 296 at drivers/clk/clk.c:952 clk_core_disable+0xa4/0xb0 ... [ 37.506986] Call trace: [ 37.509432] clk_core_disable+0xa4/0xb0 [ 37.513270] clk_disable+0x34/0x50 [ 37.516672] imx_uart_thaw+0x38/0x5c [ 37.520250] platform_pm_thaw+0x30/0x6c [ 37.524089] dpm_run_callback.constprop.0+0x3c/0xd4 [ 37.528972] device_resume+0x7c/0x160 [ 37.532633] dpm_resume+0xe8/0x230 [ 37.536036] hibernation_snapshot+0x288/0x430 [ 37.540397] hibernate+0x10c/0x2e0 [ 37.543798] state_store+0xc4/0xd0 [ 37.547203] kobj_attr_store+0x1c/0x30 [ 37.550953] sysfs_kf_write+0x48/0x60 [ 37.554619] kernfs_fop_write_iter+0x118/0x1ac [ 37.559063] new_sync_write+0xe8/0x184 [ 37.562812] vfs_write+0x230/0x290 [ 37.566214] ksys_write+0x68/0xf4 [ 37.569529] __arm64_sys_write+0x20/0x2c [ 37.573452] invoke_syscall.constprop.0+0x50/0xf0 [ 37.578156] do_el0_svc+0x11c/0x150 [ 37.581648] el0_svc+0x30/0x140 [ 37.584792] el0t_64_sync_handler+0xe8/0xf0 [ 37.588976] el0t_64_sync+0x1a0/0x1a4 [ 37.592639] ---[ end trace 56e22eec54676d75 ]---
On hibernating, pm core calls into related hooks in sequence like:
.freeze .freeze_noirq .thaw_noirq .thaw
With .thaw_noirq hook being absent, the clock will be disabled in a unbalanced call which results the warning above.
imx_uart_freeze() clk_prepare_enable() imx_uart_suspend_noirq() clk_disable() imx_uart_thaw clk_disable_unprepare()
Adding the missing .thaw_noirq hook as imx_uart_resume_noirq() will have the call sequence corrected as below and thus fix the warning.
imx_uart_freeze() clk_prepare_enable() imx_uart_suspend_noirq() clk_disable() imx_uart_resume_noirq() clk_enable() imx_uart_thaw clk_disable_unprepare()
Fixes: 09df0b3464e5 ("serial: imx: fix endless loop during suspend") Reviewed-by: Martin Kaiser martin@kaiser.cx Signed-off-by: Shawn Guo shawn.guo@linaro.org Link: https://lore.kernel.org/r/20221012121353.2346280-1-shawn.guo@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/tty/serial/imx.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 278b4033a3cc..57e3fda979ea 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -2594,6 +2594,7 @@ static const struct dev_pm_ops imx_uart_pm_ops = { .suspend_noirq = imx_uart_suspend_noirq, .resume_noirq = imx_uart_resume_noirq, .freeze_noirq = imx_uart_suspend_noirq, + .thaw_noirq = imx_uart_resume_noirq, .restore_noirq = imx_uart_resume_noirq, .suspend = imx_uart_suspend, .resume = imx_uart_resume,