RE: [PATCH v2 3/3] ACPI / sleep: EC-based wakeup from suspend-to-idle on recent Dell systems

Zheng, Lv
2017-06-19T23:37:25Z

Hi, Rafael

> From: linux-acpi-owner@vger.kernel.org [mailto:linux-acpi-owner@vger.kernel.org] On Behalf Of Rafael J.
> Wysocki
> Subject: [PATCH v2 3/3] ACPI / sleep: EC-based wakeup from suspend-to-idle on recent Dell systems
>
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> Some recent Dell laptops, including the XPS13 model numbers 9360 and
> 9365, cannot be woken up from suspend-to-idle by pressing the power
> button which is unexpected and makes that feature less usable on
> those systems. Moreover, on the 9365 ACPI S3 (suspend-to-RAM) is
> not expected to be used at all (the OS these systems ship with never
> exercises the ACPI S3 path) and suspend-to-idle is the only viable
> system suspend mechanism in there.
>
> The reason why the power button wakeup from suspend-to-idle doesn't
> work on those systems is because their power button events are
> signaled by the EC (Embedded Controller), whose GPE (General Purpose
> Event) line is disabled during suspend-to-idle transitions in Linux.
> That is done on purpose, because in general the EC tends to generate
> tons of events for various reasons (battery and thermal updates and
> similar, for example) and all of them would kick the CPUs out of deep
> idle states while in suspend-to-idle, which effectively would defeat
> its purpose.
>
> Of course, on the Dell systems in question the EC GPE must be enabled
> during suspend-to-idle transitions for the button press events to
> be signaled while suspended at all. For this reason, add a DMI
> switch to the ACPI system suspend infrastructure to treat the EC
> GPE as a wakeup one on the affected Dell systems. In case the
> users would prefer not to do that after all, add a new kernel
> command line switch, acpi_sleep=no_ec_wakeup, to disable that new
> behavior.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
>
> -> v2: Added acpi_sleep=no_ec_wakeup to prevent EC events from waking up
> the system from s2idle on systems where they do that by default.
>
> ---
> Documentation/admin-guide/kernel-parameters.txt | 6 ++-
> arch/x86/kernel/acpi/sleep.c | 2 +
> drivers/acpi/ec.c | 19 ++++++++++
> drivers/acpi/internal.h | 2 +
> drivers/acpi/sleep.c | 43 ++++++++++++++++++++++++
> include/linux/acpi.h | 1
> 6 files changed, 71 insertions(+), 2 deletions(-)
>
> Index: linux-pm/drivers/acpi/ec.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/ec.c
> +++ linux-pm/drivers/acpi/ec.c
> @@ -40,6 +40,7 @@
> #include <linux/slab.h>
> #include <linux/acpi.h>
> #include <linux/dmi.h>
> +#include <linux/suspend.h>
> #include <asm/io.h>
>
> #include "internal.h"
> @@ -1493,6 +1494,16 @@ static int acpi_ec_setup(struct acpi_ec
> acpi_handle_info(ec->handle,
> "GPE=0x%lx, EC_CMD/EC_SC=0x%lx, EC_DATA=0x%lx\n",
> ec->gpe, ec->command_addr, ec->data_addr);
> +
> + /*
> + * On some platforms the EC GPE is used for waking up the system from
> + * suspend-to-idle, so mark it as a wakeup one.
> + *
> + * This can be done unconditionally, as the setting does not matter
> + * until acpi_set_gpe_wake_mask() is called for the GPE.
> + */
> + acpi_mark_gpe_for_wake(NULL, ec->gpe);
> +
> return ret;
> }
>
> @@ -1835,8 +1846,11 @@ static int acpi_ec_suspend(struct device
> struct acpi_ec *ec =
> acpi_driver_data(to_acpi_device(dev));
>
> - if (ec_freeze_events)
> + if (!pm_suspend_via_firmware() && acpi_sleep_ec_gpe_may_wakeup())
> + acpi_set_gpe_wake_mask(NULL, ec->gpe, ACPI_GPE_ENABLE);
> + else if (ec_freeze_events)
> acpi_ec_disable_event(ec);
> +
> return 0;
> }
>
> @@ -1846,6 +1860,9 @@ static int acpi_ec_resume(struct device
> acpi_driver_data(to_acpi_device(dev));
>
> acpi_ec_enable_event(ec);
> + if (!pm_resume_via_firmware() && acpi_sleep_ec_gpe_may_wakeup())
> + acpi_set_gpe_wake_mask(NULL, ec->gpe, ACPI_GPE_DISABLE);
> +
> return 0;
> }
> #endif
> Index: linux-pm/drivers/acpi/internal.h
> ===================================================================
> --- linux-pm.orig/drivers/acpi/internal.h
> +++ linux-pm/drivers/acpi/internal.h
> @@ -199,9 +199,11 @@ void acpi_ec_remove_query_handler(struct
> -------------------------------------------------------------------------- */
> #ifdef CONFIG_ACPI_SYSTEM_POWER_STATES_SUPPORT
> extern bool acpi_s2idle_wakeup(void);
> +extern bool acpi_sleep_ec_gpe_may_wakeup(void);
> extern int acpi_sleep_init(void);
> #else
> static inline bool acpi_s2idle_wakeup(void) { return false; }
> +static inline bool acpi_sleep_ec_gpe_may_wakeup(void) { return false; }
> static inline int acpi_sleep_init(void) { return -ENXIO; }
> #endif
>
> Index: linux-pm/drivers/acpi/sleep.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/sleep.c
> +++ linux-pm/drivers/acpi/sleep.c
> @@ -160,6 +160,23 @@ static int __init init_nvs_nosave(const
> return 0;
> }
>
> +/* If set, it is allowed to use the EC GPE to wake up the system. */
> +static bool ec_gpe_wakeup_allowed __initdata = true;
> +
> +void __init acpi_disable_ec_gpe_wakeup(void)
> +{
> + ec_gpe_wakeup_allowed = false;
> +}
> +
> +/* If set, the EC GPE will be configured to wake up the system. */
> +static bool ec_gpe_wakeup;
> +
> +static int __init init_ec_gpe_wakeup(const struct dmi_system_id *d)
> +{
> + ec_gpe_wakeup = ec_gpe_wakeup_allowed;
> + return 0;
> +}
> +
> static struct dmi_system_id acpisleep_dmi_table[] __initdata = {
> {
> .callback = init_old_suspend_ordering,
> @@ -343,6 +360,26 @@ static struct dmi_system_id acpisleep_dm
> DMI_MATCH(DMI_PRODUCT_NAME, "80E3"),
> },
> },
> + /*
> + * Enable the EC to wake up the system from suspend-to-idle to allow
> + * power button events to it wake up.
> + */
> + {
> + .callback = init_ec_gpe_wakeup,
> + .ident = "Dell XPS 13 9360",
> + .matches = {
> + DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
> + DMI_MATCH(DMI_PRODUCT_NAME, "XPS 13 9360"),
> + },
> + },
> + {
> + .callback = init_ec_gpe_wakeup,
> + .ident = "Dell XPS 13 9365",
> + .matches = {
> + DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
> + DMI_MATCH(DMI_PRODUCT_NAME, "XPS 13 9365"),
> + },
> + },
> {},
> };
>

I have a concern here.

ACPI spec has already defined a mechanism to statically
Mark GPEs as wake-capable and enable it, it is done via
_PRW. We may call it a "static wakeup GPE" mechanism.

Now the problem might be on some platforms, _PRW cannot be
prepared unconditionally. And the platform designers wants
a "dynamic wakeup GPE" mechanism to dynamically
mark/enable GPEs as wakeup GPE after having done some
platform specific behaviors (ex., after/before
saving/restoring some firmware configurations).

>From this point of view, can we prepare several APIs in
sleep.c to allow dynamically mark/enable wakeup GPEs and
export EC information via a new API from ec.c, ex.,
acpi_ec_get_attributes(), or just publish struct acpi_ec
and first_ec in acpi_ec.h to the other drivers.
So that all such kinds of platforms drivers can use both
interfaces to dynamically achieve this, which can help
to avoid introducing quirk tables here.

Thanks and best regards
Lv

> @@ -485,6 +522,7 @@ static void acpi_pm_end(void)
> }
> #else /* !CONFIG_ACPI_SLEEP */
> #define acpi_target_sleep_state ACPI_STATE_S0
> +#define ec_gpe_wakeup false
> static inline void acpi_sleep_dmi_check(void) {}
> #endif /* CONFIG_ACPI_SLEEP */
>
> @@ -740,6 +778,11 @@ bool acpi_s2idle_wakeup(void)
> return s2idle_wakeup;
> }
>
> +bool acpi_sleep_ec_gpe_may_wakeup(void)
> +{
> + return ec_gpe_wakeup;
> +}
> +
> #ifdef CONFIG_PM_SLEEP
> static u32 saved_bm_rld;
>
> Index: linux-pm/arch/x86/kernel/acpi/sleep.c
> ===================================================================
> --- linux-pm.orig/arch/x86/kernel/acpi/sleep.c
> +++ linux-pm/arch/x86/kernel/acpi/sleep.c
> @@ -137,6 +137,8 @@ static int __init acpi_sleep_setup(char
> acpi_nvs_nosave_s3();
> if (strncmp(str, "old_ordering", 12) == 0)
> acpi_old_suspend_ordering();
> + if (strncmp(str, "no_ec_wakeup", 12) == 0)
> + acpi_disable_ec_gpe_wakeup();
> str = strchr(str, ',');
> if (str != NULL)
> str += strspn(str, ", \t");
> Index: linux-pm/include/linux/acpi.h
> ===================================================================
> --- linux-pm.orig/include/linux/acpi.h
> +++ linux-pm/include/linux/acpi.h
> @@ -448,6 +448,7 @@ void __init acpi_no_s4_hw_signature(void
> void __init acpi_old_suspend_ordering(void);
> void __init acpi_nvs_nosave(void);
> void __init acpi_nvs_nosave_s3(void);
> +void __init acpi_disable_ec_gpe_wakeup(void);
> #endif /* CONFIG_PM_SLEEP */
>
> struct acpi_osc_context {
> Index: linux-pm/Documentation/admin-guide/kernel-parameters.txt
> ===================================================================
> --- linux-pm.orig/Documentation/admin-guide/kernel-parameters.txt
> +++ linux-pm/Documentation/admin-guide/kernel-parameters.txt
> @@ -223,7 +223,8 @@
>
> acpi_sleep= [HW,ACPI] Sleep options
> Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
> - old_ordering, nonvs, sci_force_enable }
> + old_ordering, nonvs, sci_force_enable,
> + no_ec_wakeup }
> See Documentation/power/video.txt for information on
> s3_bios and s3_mode.
> s3_beep is for debugging; it makes the PC's speaker beep
> @@ -239,6 +240,9 @@
> sci_force_enable causes the kernel to set SCI_EN directly
> on resume from S1/S3 (which is against the ACPI spec,
> but some broken systems don't work without it).
> + no_ec_wakeup prevents the EC GPE from being configured
> + to wake up the system on platforms where that is done by
> + default.
>
> acpi_use_timer_override [HW,ACPI]
> Use timer override. For some broken Nvidia NF5 boards
>
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