On Tue, Nov 18, 2025 at 12:52:14PM +0000, Daniel Thompson wrote:
On Fri, Nov 14, 2025 at 02:09:56PM +0000, Mark Brown wrote:On Thu, Jul 31, 2025 at 10:47:18AM +0200, Michael Grzeschik wrote: > Currently when calling pwm_apply_might_sleep in the probe routine > the pwm will be configured with an not fully defined state. > > The duty_cycle is not yet set in that moment. There is a final > backlight_update_status call that will have a properly setup state. > However this change in the backlight can create a short flicker if the > backlight was already preinitialised.I'm seeing the libre.computer Renegade Elite producing warnings during boot in -next which bisect to this patch. The warnings are: [ 24.175095] input: adc-keys as /devices/platform/adc-keys/input/input1 [ 24.176612] ------------[ cut here ]------------ [ 24.177048] WARNING: CPU: 0 PID: 0 at kernel/context_tracking.c:127 ct_kernel_exit.constprop.0+0x98/0xa0 ... [ 24.190106] Call trace: [ 24.190325] ct_kernel_exit.constprop.0+0x98/0xa0 (P) [ 24.190775] ct_idle_enter+0x10/0x20 [ 24.191096] cpuidle_enter_state+0x1fc/0x320 [ 24.191476] cpuidle_enter+0x38/0x50 [ 24.191802] do_idle+0x1e4/0x260 [ 24.192094] cpu_startup_entry+0x34/0x3c [ 24.192444] rest_init+0xdc/0xe0 [ 24.192734] console_on_rootfs+0x0/0x6c [ 24.193082] __primary_switched+0x88/0x90 [ 24.193445] ---[ end trace 0000000000000000 ]--- which seems a little surprising but there is some console stuff there that looks relevant. Full log: https://lava.sirena.org.uk/scheduler/job/2086528#L897Michael, reading these logs it looks to me like the underlying oops is this backtrace (which makes a lot more sense given the code you altered): [ 24.133631] Call trace: [ 24.133853] pwm_backlight_probe+0x830/0x868 [pwm_bl] (P) [ 24.134341] platform_probe+0x5c/0xa4 [ 24.134679] really_probe+0xbc/0x2c0 [ 24.135001] __driver_probe_device+0x78/0x120 [ 24.135391] driver_probe_device+0x3c/0x154 [ 24.135765] __driver_attach+0x90/0x1a0 [ 24.136111] bus_for_each_dev+0x7c/0xdc [ 24.136462] driver_attach+0x24/0x38 [ 24.136785] bus_add_driver+0xe4/0x208 [ 24.137124] driver_register+0x68/0x130 [ 24.137468] __platform_driver_register+0x24/0x30 [ 24.137888] pwm_backlight_driver_init+0x20/0x1000 [pwm_bl] [ 24.138389] do_one_initcall+0x60/0x1d4 [ 24.138735] do_init_module+0x54/0x23c [ 24.139073] load_module+0x1760/0x1cf0 [ 24.139407] init_module_from_file+0x88/0xcc [ 24.139787] __arm64_sys_finit_module+0x1bc/0x338 [ 24.140207] invoke_syscall+0x48/0x104 [ 24.140549] el0_svc_common.constprop.0+0x40/0xe0 [ 24.140970] do_el0_svc+0x1c/0x28 [ 24.141268] el0_svc+0x34/0xec [ 24.141548] el0t_64_sync_handler+0xa0/0xf0 [ 24.141920] el0t_64_sync+0x198/0x19c Should we back out the patch for now?
I would be fine with that. But actually I would like to see the proof that without the patch, this backtrace will not trigger. Looking through the codepath, I could not directly find a case where this should happen. Mark, is there a way to rerun this without my patch? Michael -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
signature.asc
Description: PGP signature
