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Date: Wed, 1 Apr 2020 18:32:41 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Hans de Goede <hdegoede@...hat.com>
Cc: "Rafael J . Wysocki" <rjw@...ysocki.net>,
Len Brown <lenb@...nel.org>,
Darren Hart <dvhart@...radead.org>,
Andy Shevchenko <andy@...radead.org>,
ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
Platform Driver <platform-driver-x86@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
"5 . 4+" <stable@...r.kernel.org>
Subject: Re: [PATCH 5.6 regression fix 1/2] ACPI: PM: Add acpi_s2idle_register_wake_callback()
On Mon, Mar 30, 2020 at 12:34 AM Hans de Goede <hdegoede@...hat.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_s2idle_register_wake_callback() function which registers
> a callback to be called from acpi_s2idle_wake() and when the callback
> 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.
>
> Fixes: fdde0ff8590b ("ACPI: PM: s2idle: Prevent spurious SCIs from waking up the system")
> Cc: 5.4+ <stable@...r.kernel.org> # 5.4+
> Signed-off-by: Hans de Goede <hdegoede@...hat.com>
I generally agree with the approach, but I would make some, mostly
cosmetic, changes.
First off, I'd put the new code into drivers/acpi/wakeup.c.
I'd export one function from there to be called from
acpi_s2idle_wake() and the install/uninstall routines for the users.
> ---
> drivers/acpi/sleep.c | 70 ++++++++++++++++++++++++++++++++++++++++++++
> include/linux/acpi.h | 7 +++++
> 2 files changed, 77 insertions(+)
>
> diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
> index e5f95922bc21..e360e51afa8e 100644
> --- a/drivers/acpi/sleep.c
> +++ b/drivers/acpi/sleep.c
> @@ -943,6 +943,65 @@ static struct acpi_scan_handler lps0_handler = {
> .attach = lps0_device_attach,
> };
>
> +struct s2idle_wake_callback {
I'd call this acpi_wakeup_handler.
> + struct list_head list;
list_node?
> + bool (*function)(void *data);
bool (*wakeup)(void *context)?
> + void *user_data;
context?
> +};
> +
> +static LIST_HEAD(s2idle_wake_callback_head);
> +static DEFINE_MUTEX(s2idle_wake_callback_mutex);
> +
> +/*
> + * Drivers which may share an IRQ with the SCI can use this to register
> + * a callback which returns true when the device they are managing wants
> + * to trigger a wakeup.
> + */
> +int acpi_s2idle_register_wake_callback(
> + int wake_irq, bool (*function)(void *data), void *user_data)
> +{
> + struct s2idle_wake_callback *callback;
> +
> + /*
> + * If the device is not sharing its IRQ with the SCI, there is no
> + * need to register the callback.
> + */
> + if (!acpi_sci_irq_valid() || wake_irq != acpi_sci_irq)
> + return 0;
> +
> + callback = kmalloc(sizeof(*callback), GFP_KERNEL);
> + if (!callback)
> + return -ENOMEM;
> +
> + callback->function = function;
> + callback->user_data = user_data;
> +
> + mutex_lock(&s2idle_wake_callback_mutex);
> + list_add(&callback->list, &s2idle_wake_callback_head);
> + mutex_unlock(&s2idle_wake_callback_mutex);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(acpi_s2idle_register_wake_callback);
> +
> +void acpi_s2idle_unregister_wake_callback(
> + bool (*function)(void *data), void *user_data)
> +{
> + struct s2idle_wake_callback *cb;
> +
> + mutex_lock(&s2idle_wake_callback_mutex);
> + list_for_each_entry(cb, &s2idle_wake_callback_head, list) {
> + if (cb->function == function &&
> + cb->user_data == user_data) {
> + list_del(&cb->list);
> + kfree(cb);
> + break;
> + }
> + }
> + mutex_unlock(&s2idle_wake_callback_mutex);
> +}
> +EXPORT_SYMBOL_GPL(acpi_s2idle_unregister_wake_callback);
> +
> static int acpi_s2idle_begin(void)
> {
> acpi_scan_lock_acquire();
> @@ -992,6 +1051,8 @@ static void acpi_s2idle_sync(void)
>
> static bool acpi_s2idle_wake(void)
> {
> + struct s2idle_wake_callback *cb;
> +
> if (!acpi_sci_irq_valid())
> return pm_wakeup_pending();
>
> @@ -1025,6 +1086,15 @@ static bool acpi_s2idle_wake(void)
> if (acpi_any_gpe_status_set() && !acpi_ec_dispatch_gpe())
> return true;
>
> + /*
> + * Check callbacks registered by drivers sharing the SCI.
> + * Note no need to lock, nothing else is running.
> + */
> + list_for_each_entry(cb, &s2idle_wake_callback_head, list) {
> + if (cb->function(cb->user_data))
> + return true;
> + }
AFAICS this needs to be done in acpi_s2idle_restore() too to clear the
status bits in case one of these wakeup sources triggers along with a
GPE or a fixed event and the other one wins the race.
> +
> /*
> * Cancel the wakeup and process all pending events in case
> * there are any wakeup ones in there.
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index 0f24d701fbdc..9f06e1dc79c1 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -488,6 +488,13 @@ void __init acpi_nvs_nosave_s3(void);
> void __init acpi_sleep_no_blacklist(void);
> #endif /* CONFIG_PM_SLEEP */
>
> +#ifdef CONFIG_ACPI_SYSTEM_POWER_STATES_SUPPORT
> +int acpi_s2idle_register_wake_callback(
> + int wake_irq, bool (*function)(void *data), void *user_data);
> +void acpi_s2idle_unregister_wake_callback(
> + bool (*function)(void *data), void *user_data);
> +#endif
> +
> struct acpi_osc_context {
> char *uuid_str; /* UUID string */
> int rev;
> --
Thanks!
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