On Wed, Oct 12, 2022 at 08:13:53PM +0800, Shawn Guo wrote: > 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() > > Signed-off-by: Shawn Guo <shawn.guo@xxxxxxxxxx> What commit id does this fix, and does it need to go to older/stable kernels? thanks, greg k-h
