On 09/04/2026 3:49 pm, Leo Yan wrote:
On Thu, Apr 09, 2026 at 03:30:56PM +0100, James Clark wrote:
[...]
@@ -1759,16 +1760,36 @@ static int coresight_pm_check(struct coresight_path *path) if (source_has_cb) return 1; + sink_has_cb = coresight_ops(sink)->pm_save_disable && + coresight_ops(sink)->pm_restore_enable; + /* + * It is not permitted that the source has no callbacks while the sink + * does, as the sink cannot be disabled without disabling the source, + * which may lead to lockups. Alternatively, the ETM driver should + * enable self-hosted PM mode at probe (see etm4_probe()). + */ + if (sink_has_cb) { + pr_warn_once("coresight PM failed: source has no PM callbacks; " + "cannot safely control sink\n");
This prints out on my Orion board on a fresh boot because of how pm_save_enable is setup there. Do we really need the configuration of pm_save_enable for ETE/TRBE if we know that it always needs saving?
Yeah, I can remove this check and always bind CPU PM ops for ETE.
It also stops warning if I rmmod and modprobe the module after booting. Seems like pm_save_enable is different depending on how the module is loaded which doesn't seem right.
Thats because the warning is pr_warn_*once*()
I don't think so, I tested it with a printf instead of a warn once and also tested modprobeing straight after a reboot.
I am a bit surprised that Orion6 hits the CPU idle flow, as I observed that idle states are not enabled on my board:
# ls /sys/devices/system/cpu/cpu*/cpuidle ls: cannot access '/sys/devices/system/cpu/cpu*/cpuidle': No such file or directory
/sys/devices/system/cpu/cpu0/cpuidle: total 0 drwxr-xr-x 9 root 0 Apr 10 10:08 .. drwxr-xr-x 2 root 0 Apr 10 10:10 state2 drwxr-xr-x 2 root 0 Apr 10 10:10 state1 drwxr-xr-x 2 root 0 Apr 10 10:10 state0 drwxr-xr-x 2 root 0 Apr 10 10:10 driver drwxr-xr-x 6 root 0 Apr 10 10:10 .
If you hit only once CPU idle notifier, it is good to add a dump_stack() in coresight_cpu_pm_notify and print the "cmd" argument, so we can know the calling coming from where. I am a bit suspect it might be a glitch in CPUIdle layer.
Thanks, Leo
cmd: 2
[ 7.878456] coresight_cpu_pm_notify+0x148/0x4b0 [ 7.878462] notifier_call_chain+0x8c/0x1e0 [ 7.878467] raw_notifier_call_chain+0x24/0x38 [ 7.878469] cpu_pm_exit+0x34/0x68 [ 7.878472] acpi_processor_ffh_lpi_enter+0x40/0x78 [ 7.878476] acpi_idle_lpi_enter+0x54/0x78 [ 7.878481] cpuidle_enter_state+0xb4/0x250 [ 7.878483] cpuidle_enter+0x44/0x68 [ 7.878487] do_idle+0x1e0/0x278 [ 7.878492] cpu_startup_entry+0x40/0x50 [ 7.878495] rest_init+0xec/0xf8 [ 7.878497] start_kernel+0x348/0x400 [ 7.878503] __primary_switched+0x88/0x98
-> zcat /proc/config.gz | grep IDLE CONFIG_CONTEXT_TRACKING_IDLE=y CONFIG_NO_HZ_IDLE=y CONFIG_CPU_IDLE=y CONFIG_CPU_IDLE_MULTIPLE_DRIVERS=y # CONFIG_CPU_IDLE_GOV_LADDER is not set CONFIG_CPU_IDLE_GOV_MENU=y # CONFIG_CPU_IDLE_GOV_TEO is not set CONFIG_DT_IDLE_STATES=y CONFIG_DT_IDLE_GENPD=y CONFIG_ARM_PSCI_CPUIDLE=y CONFIG_ARM_PSCI_CPUIDLE_DOMAIN=y CONFIG_ACPI_PROCESSOR_IDLE=y CONFIG_GENERIC_SMP_IDLE_THREAD=y CONFIG_GENERIC_IDLE_POLL_SETUP=y # CONFIG_IDLE_PAGE_TRACKING is not set # CONFIG_NETFILTER_XT_TARGET_IDLETIMER is not set