[PATCH v10 00/20] CoreSight: Refactor power management for CoreSight path

[Jie Gan]

On 4/14/2026 12:31 AM, Leo Yan wrote:
> On Mon, Apr 13, 2026 at 06:30:18PM +0800, Jie Gan wrote:
> 
> [...]
> 
>> tested on QCOM sa8775-ride:
>>
>> === 1. Sysfs mode: basic enable/disable ===
>> PASS: Sink tmc_etr0 enabled
>> PASS: Source etm0 enabled
>> PASS: Source etm0 disabled cleanly
>> PASS: Sink tmc_etr0 disabled cleanly
>>
>> === 2. Sysfs mode: repeated enable/disable cycles (10x) ===
>> PASS: 10 enable/disable cycles completed without error
>>
>> === 3. Sysfs mode: enable source with no active sink ===
>> PASS: Enable without sink returned error (expected)
>>
>> === 4. Sysfs mode: enable/disable all per-CPU sources ===
>>      etm0 (cpu0): enabled OK
>>      etm1 (cpu1): enabled OK
>>      etm2 (cpu2): enabled OK
>>      etm3 (cpu3): enabled OK
>>      etm4 (cpu4): enabled OK
>>      etm5 (cpu5): enabled OK
>>      etm6 (cpu6): enabled OK
>>      etm7 (cpu7): enabled OK
>> PASS: All online per-CPU sources enabled/disabled successfully
>>
>> === 5. CPU hotplug: offline CPU while sysfs tracing active ===
>>    Using source etm1 on cpu1
>>    Tracing active on cpu1, offlining CPU...
>> [   82.805359] psci: CPU1 killed (polled 0 ms)
>> PASS: Source auto-disabled on CPU offline
>> [   83.346033] Detected PIPT I-cache on CPU1
>> [   83.346114] GICv3: CPU1: found redistributor 100 region
>> 0:0x0000000017a80000
>> [   83.346283] CPU1: Booted secondary processor 0x0000000100 [0x410fd4b2]
>> PASS: Source re-enabled after CPU re-online
>>
>> === 6. Sysfs: enable source on offline CPU (expect ENODEV) ===
>> [   84.013788] psci: CPU1 killed (polled 0 ms)
>> PASS: Enable on offline cpu1 rejected (enable_source=0)
>> [   84.349558] Detected PIPT I-cache on CPU1
>> [   84.349640] GICv3: CPU1: found redistributor 100 region
>> 0:0x0000000017a80000
>> [   84.349811] CPU1: Booted secondary processor 0x0000000100 [0x410fd4b2]
>>
>> === 7. CPU PM: trace survives CPU idle entry/exit ===
>>    Sleeping 3s to allow CPU idle entry...
>>    Idle entries on cpu0 during test: 35
>> PASS: Source still enabled after idle (PM save/restore working)
>>
>> === 8. Perf mode: basic cs_etm recording ===
>> SKIP: perf not found in PATH
>>
>> === 11. TRBE: check save/restore sysfs nodes (if present) ===
>> SKIP: No TRBE devices found
>>
>> Tested-by: Jie Gan <jie.gan at oss.qualcomm.com>
> 
> Just heads up: since Sashiko [1] pointed out a corner case where an SMP call
> may fail when disabling the source device, the per-CPU path pointer
> might not be cleared.  If the ETMv4 device is then removed (e.g. if the
> user unloads the ETMv4 module), CPU PM notifier might access the stale
> path pointer.  Though this is a rare case, we should handle it safely.
> This is why the series was not picked for the v7.1 merge window.
> 
> Thanks a lot for the testing, Jie! It's very helpful, and I will add
> your test tags in the next spin.
> 
> Anyway, please expect more iterations.

Noted, will run the test cases on new iterations.

Thanks,
Jie

> 
> Thanks,
> Leo
> 
> [1] https://sashiko.dev/#/patchset/20260405-arm_coresight_path_power_management_improvement-v10-0-13e94754a8be%40arm.com?part=5