Re: [PATCH v2 1/2] ACPI: PM: Add acpi_[un]register_wakeup_handler()

[Andy Shevchenko <andy.shevchenko@gmail.com>]

On Fri, Apr 3, 2020 at 1:52 PM Hans de Goede <hdegoede@redhat.com> wrote:
>
> Since commit fdde0ff8590b ("ACPI: PM: s2idle: Prevent spurious SCIs from
> waking up the system") the SCI triggering without there being a wakeup
> cause recognized by the ACPI sleep code will no longer wakeup the system.
>
> This works as intended, but this is a problem for devices where the SCI
> is shared with another device which is also a wakeup source.
>
> In the past these, from the pov of the ACPI sleep code, spurious SCIs
> would still cause a wakeup so the wakeup from the device sharing the
> interrupt would actually wakeup the system. This now no longer works.
>
> This is a problem on e.g. Bay Trail-T and Cherry Trail devices where
> some peripherals (typically the XHCI controller) can signal a
> Power Management Event (PME) to the Power Management Controller (PMC)
> to wakeup the system, this uses the same interrupt as the SCI.
> These wakeups are handled through a special INT0002 ACPI device which
> checks for events in the GPE0a_STS for this and takes care of acking
> the PME so that the shared interrupt stops triggering.
>
> The change to the ACPI sleep code to ignore the spurious SCI, causes
> the system to no longer wakeup on these PME events. To make things
> worse this means that the INT0002 device driver interrupt handler will
> no longer run, causing the PME to not get cleared and resulting in the
> system hanging. Trying to wakeup the system after such a PME through e.g.
> the power button no longer works.
>
> Add an acpi_register_wakeup_handler() function which registers
> a handler to be called from acpi_s2idle_wake() and when the handler
> returns true, return true from acpi_s2idle_wake().
>
> The INT0002 driver will use this mechanism to check the GPE0a_STS
> register from acpi_s2idle_wake() and to tell the system to wakeup
> if a PME is signaled in the register.
>

Something happened to your editor settings? Some lines looks like too short...

> Fixes: fdde0ff8590b ("ACPI: PM: s2idle: Prevent spurious SCIs from waking up the system")
> Cc: 5.4+ <stable@vger.kernel.org> # 5.4+
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
> Changes in v2:
> - Move the new helpers to drivers/acpi/wakeup.c
> - Rename the helpers to acpi_[un]register_wakeup_handler(), also give some
>   types/variables better names
> ---
>  drivers/acpi/sleep.c  |  4 +++
>  drivers/acpi/sleep.h  |  1 +
>  drivers/acpi/wakeup.c | 82 +++++++++++++++++++++++++++++++++++++++++++
>  include/linux/acpi.h  |  5 +++
>  4 files changed, 92 insertions(+)
>
> diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
> index e5f95922bc21..dc8c71c47285 100644
> --- a/drivers/acpi/sleep.c
> +++ b/drivers/acpi/sleep.c
> @@ -1025,6 +1025,10 @@ static bool acpi_s2idle_wake(void)
>                 if (acpi_any_gpe_status_set() && !acpi_ec_dispatch_gpe())
>                         return true;
>
> +               /* Check wakeups from drivers sharing the SCI. */
> +               if (acpi_check_wakeup_handlers())
> +                       return true;
> +
>                 /*
>                  * Cancel the wakeup and process all pending events in case
>                  * there are any wakeup ones in there.
> diff --git a/drivers/acpi/sleep.h b/drivers/acpi/sleep.h
> index 41675d24a9bc..3d90480ce1b1 100644
> --- a/drivers/acpi/sleep.h
> +++ b/drivers/acpi/sleep.h
> @@ -2,6 +2,7 @@
>
>  extern void acpi_enable_wakeup_devices(u8 sleep_state);
>  extern void acpi_disable_wakeup_devices(u8 sleep_state);
> +extern bool acpi_check_wakeup_handlers(void);
>
>  extern struct list_head acpi_wakeup_device_list;
>  extern struct mutex acpi_device_lock;
> diff --git a/drivers/acpi/wakeup.c b/drivers/acpi/wakeup.c
> index 9614126bf56e..de0f8e626c1c 100644
> --- a/drivers/acpi/wakeup.c
> +++ b/drivers/acpi/wakeup.c
> @@ -12,6 +12,15 @@
>  #include "internal.h"
>  #include "sleep.h"
>
> +struct acpi_wakeup_handler {
> +       struct list_head list_node;
> +       bool (*wakeup)(void *context);
> +       void *context;
> +};
> +
> +static LIST_HEAD(acpi_wakeup_handler_head);
> +static DEFINE_MUTEX(acpi_wakeup_handler_mutex);
> +
>  /*
>   * We didn't lock acpi_device_lock in the file, because it invokes oops in
>   * suspend/resume and isn't really required as this is called in S-state. At
> @@ -96,3 +105,76 @@ int __init acpi_wakeup_device_init(void)
>         mutex_unlock(&acpi_device_lock);
>         return 0;
>  }
> +
> +/**
> + * acpi_register_wakeup_handler - Register wakeup handler
> + * @wake_irq: The IRQ through which the device may receive wakeups
> + * @wakeup:   Wakeup-handler to call when the SCI has triggered a wakeup
> + * @context:  Context to pass to the handler when calling it
> + *
> + * Drivers which may share an IRQ with the SCI can use this to register
> + * a handler which returns true when the device they are managing wants
> + * to trigger a wakeup.
> + */

> +int acpi_register_wakeup_handler(

...this one...

> +       int wake_irq, bool (*wakeup)(void *context), void *context)
> +{
> +       struct acpi_wakeup_handler *handler;
> +
> +       /*
> +        * If the device is not sharing its IRQ with the SCI, there is no
> +        * need to register the handler.
> +        */
> +       if (!acpi_sci_irq_valid() || wake_irq != acpi_sci_irq)
> +               return 0;
> +
> +       handler = kmalloc(sizeof(*handler), GFP_KERNEL);
> +       if (!handler)
> +               return -ENOMEM;
> +
> +       handler->wakeup = wakeup;
> +       handler->context = context;
> +
> +       mutex_lock(&acpi_wakeup_handler_mutex);
> +       list_add(&handler->list_node, &acpi_wakeup_handler_head);
> +       mutex_unlock(&acpi_wakeup_handler_mutex);
> +
> +       return 0;
> +}
> +EXPORT_SYMBOL_GPL(acpi_register_wakeup_handler);
> +
> +/**
> + * acpi_unregister_wakeup_handler - Unregister wakeup handler
> + * @wakeup:   Wakeup-handler passed to acpi_register_wakeup_handler()
> + * @context:  Context passed to acpi_register_wakeup_handler()
> + */

> +void acpi_unregister_wakeup_handler(
> +       bool (*wakeup)(void *context), void *context)

Not sure, but looks like short.

> +{
> +       struct acpi_wakeup_handler *handler;
> +
> +       mutex_lock(&acpi_wakeup_handler_mutex);
> +       list_for_each_entry(handler, &acpi_wakeup_handler_head, list_node) {

> +               if (handler->wakeup == wakeup &&
> +                   handler->context == context) {

Ditto.

> +                       list_del(&handler->list_node);
> +                       kfree(handler);
> +                       break;
> +               }
> +       }
> +       mutex_unlock(&acpi_wakeup_handler_mutex);
> +}
> +EXPORT_SYMBOL_GPL(acpi_unregister_wakeup_handler);
> +
> +bool acpi_check_wakeup_handlers(void)
> +{
> +       struct acpi_wakeup_handler *handler;
> +
> +       /* No need to lock, nothing else is running when we're called. */
> +       list_for_each_entry(handler, &acpi_wakeup_handler_head, list_node) {
> +               if (handler->wakeup(handler->context))
> +                       return true;
> +       }
> +
> +       return false;
> +}
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index 0f24d701fbdc..efac0f9c01a2 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -488,6 +488,11 @@ void __init acpi_nvs_nosave_s3(void);
>  void __init acpi_sleep_no_blacklist(void);
>  #endif /* CONFIG_PM_SLEEP */
>
> +int acpi_register_wakeup_handler(
> +       int wake_irq, bool (*wakeup)(void *context), void *context);
> +void acpi_unregister_wakeup_handler(
> +       bool (*wakeup)(void *context), void *context);
> +
>  struct acpi_osc_context {
>         char *uuid_str;                 /* UUID string */
>         int rev;
> --
> 2.26.0
>


-- 
With Best Regards,
Andy Shevchenko