Regression in PMC code in 6.12-rc1

[Luca Coelho <luca@coelho.fi>]

Hi Marek et al,

We have been facing some errors when running some of our Display CI
tests that seem to have been introduced by the following commit:

e86c8186d03a ("platform/x86:intel/pmc: Enable the ACPI PM Timer to be turned off when suspended")

The errors we are getting look like this:

<4> [222.857770] =============================
<4> [222.857771] [ BUG: Invalid wait context ]
<4> [222.857772] 6.12.0-rc1-xe #1 Not tainted
<4> [222.857773] -----------------------------
<4> [222.857774] swapper/4/0 is trying to lock:
<4> [222.857775] ffff8881174c88c8 (&pmcdev->lock){+.+.}-{3:3}, at: pmc_core_acpi_pm_timer_suspend_resume+0x50/0xe0 [intel_pmc_core]
<4> [222.857782] other info that might help us debug this:
<4> [222.857783] context-{4:4}
<4> [222.857784] 1 lock held by swapper/4/0:
<4> [222.857785]  #0: ffffffff83452258 (tick_freeze_lock){....}-{2:2}, at: tick_freeze+0x16/0x110
<4> [222.857791] stack backtrace:
<4> [222.857793] CPU: 4 UID: 0 PID: 0 Comm: swapper/4 Not tainted 6.12.0-rc1-xe #1
<4> [222.857794] Hardware name: Intel Corporation Alder Lake Client Platform/AlderLake-P DDR5 RVP, BIOS RPLPFWI1.R00.4035.A00.2301200723 01/20/2023
<4> [222.857796] Call Trace:
<4> [222.857797]  <TASK>
<4> [222.857798]  dump_stack_lvl+0x80/0xc0
<4> [222.857802]  dump_stack+0x10/0x20
<4> [222.857805]  __lock_acquire+0x943/0x2800
<4> [222.857808]  ? stack_trace_save+0x4b/0x70
<4> [222.857812]  lock_acquire+0xc5/0x2f0
<4> [222.857814]  ? pmc_core_acpi_pm_timer_suspend_resume+0x50/0xe0 [intel_pmc_core]
<4> [222.857817]  __mutex_lock+0xbe/0xc70
<4> [222.857819]  ? pmc_core_acpi_pm_timer_suspend_resume+0x50/0xe0 [intel_pmc_core]
<4> [222.857822]  ? pmc_core_acpi_pm_timer_suspend_resume+0x50/0xe0 [intel_pmc_core]
<4> [222.857825]  mutex_lock_nested+0x1b/0x30
<4> [222.857827]  ? mutex_lock_nested+0x1b/0x30
<4> [222.857828]  pmc_core_acpi_pm_timer_suspend_resume+0x50/0xe0 [intel_pmc_core]
<4> [222.857831]  acpi_pm_suspend+0x23/0x40
<4> [222.857834]  clocksource_suspend+0x2b/0x50
<4> [222.857836]  timekeeping_suspend+0x22a/0x360
<4> [222.857839]  tick_freeze+0x89/0x110
<4> [222.857840]  enter_s2idle_proper+0x34/0x1d0
<4> [222.857843]  cpuidle_enter_s2idle+0xaa/0x120
<4> [222.857845]  ? tsc_verify_tsc_adjust+0x42/0x100
<4> [222.857849]  do_idle+0x221/0x250
<4> [222.857852]  cpu_startup_entry+0x29/0x30
<4> [222.857854]  start_secondary+0x12e/0x160
<4> [222.857856]  common_startup_64+0x13e/0x141
<4> [222.857859]  </TASK>

And the full logs can be found, for example, here: 

https://intel-gfx-ci.01.org/tree/intel-xe/xe-2016-92d12099cc768f36cf676ee1b014442a5c5ba965/shard-adlp-3/igt@kms_flip@flip-vs-suspend-interruptible.html


Reverting this commit seems to prevent the problem.  Do you have any
idea what could be causing this and, more importantly, how to fix it?
:)

Thanks!

--
Cheers,
Luca.