Re: [PATCH 2/3] PM: hibernate: Add platform_enter hibernation test level

[Rafael J. Wysocki]

On Mon, May 18, 2026 at 11:34 PM Nícolas F. R. A. Prado
<nfraprado@xxxxxxxxxxxxx> wrote:
>
> Add a 'platform_enter' hibernation test level to allow testing the full
> hibernation path up until the last point of return in
> hibernation_platform_enter().
>
> In particular this allows seeing print messages from the code run after
> the hibernation image is created on platforms that don't have an easily
> accessible serial console, since these messages are not present upon
> hibernation resume.
>
> Signed-off-by: Nícolas F. R. A. Prado <nfraprado@xxxxxxxxxxxxx>
> ---
>  kernel/power/hibernate.c | 13 +++++++++++--
>  kernel/power/main.c      |  1 +
>  kernel/power/power.h     |  1 +
>  3 files changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> index 001e4556b137..15cb7a090770 100644
> --- a/kernel/power/hibernate.c
> +++ b/kernel/power/hibernate.c
> @@ -75,6 +75,7 @@ enum {
>  static int hibernation_mode = HIBERNATION_SHUTDOWN;
>
>  bool freezer_test_done;
> +bool platform_enter_test_done;
>
>  static const struct platform_hibernation_ops *hibernation_ops;
>
> @@ -636,6 +637,11 @@ int hibernation_platform_enter(void)
>                 goto Power_up;
>         }
>
> +       if (hibernation_test(TEST_PLATFORM_ENTER)) {
> +               platform_enter_test_done = true;
> +               goto Power_up;
> +       }
> +
>         hibernation_ops->enter();
>         /* We should never get here */
>         while (1);
> @@ -700,6 +706,8 @@ static int power_down(void)
>                 break;
>         case HIBERNATION_PLATFORM:
>                 error = hibernation_platform_enter();
> +               if (platform_enter_test_done)
> +                       goto exit;
>                 if (error == -EAGAIN || error == -EBUSY) {
>                         events_check_enabled = false;
>                         pr_info("Wakeup event detected during hibernation, rolling back.\n");
> @@ -848,7 +856,7 @@ int hibernate(void)
>                         else
>                                 error = power_down();
>                 }
> -               if (error) {
> +               if (error || platform_enter_test_done) {
>                         /* recover any devices that refused to thaw */
>                         dpm_resume_suspended_devices(PMSG_RECOVER);
>                 }
> @@ -870,8 +878,9 @@ int hibernate(void)
>         }
>         thaw_processes();
>
> -       /* Don't bother checking whether freezer_test_done is true */
> +       /* Don't bother checking whether any of the test_done flags are true */
>         freezer_test_done = false;
> +       platform_enter_test_done = false;
>   Exit:
>         filesystems_thaw();
>         pm_notifier_call_chain(PM_POST_HIBERNATION);
> diff --git a/kernel/power/main.c b/kernel/power/main.c
> index 7f53ef65b789..04f0c429519c 100644
> --- a/kernel/power/main.c
> +++ b/kernel/power/main.c
> @@ -273,6 +273,7 @@ static const char * const pm_tests[__TEST_AFTER_LAST] = {
>         [TEST_PLATFORM] = "platform",
>         [TEST_DEVICES] = "devices",
>         [TEST_FREEZER] = "freezer",
> +       [TEST_PLATFORM_ENTER] = "platform_enter",
>  };
>
>  static ssize_t pm_test_show(struct kobject *kobj, struct kobj_attribute *attr,
> diff --git a/kernel/power/power.h b/kernel/power/power.h
> index 7ccd709af93f..0d33d0e46ed0 100644
> --- a/kernel/power/power.h
> +++ b/kernel/power/power.h
> @@ -259,6 +259,7 @@ enum {
>         TEST_PLATFORM,
>         TEST_DEVICES,
>         TEST_FREEZER,
> +       TEST_PLATFORM_ENTER,
>         /* keep last */
>         __TEST_AFTER_LAST
>  };
>

In the first place, test levels are designed to be applicable to both
system suspend and hibernation and I don't see how this test can be
applied to system suspend.

Second, the last device power off transition during hibernation may
not be reversible and adding a test that goes past a point of no
return is not particularly useful.