> -----Original Message-----
> From: Srinivas Pandruvada [mailto:srinivas.pandruv...@linux.intel.com]
> Sent: Tuesday, August 8, 2017 5:41 PM
> To: r...@rjwysocki.net; l...@kernel.org
> Cc: linux...@vger.kernel.org; Limonciello, Mario <mario_limoncie...@dell.com>;
> linux-kernel@vger.kernel.org; linux-a...@vger.kernel.org; lu...@wunner.de;
> Srinivas Pandruvada <srinivas.pandruv...@linux.intel.com>
> Subject: [PATCH v2 2/2] ACPI / Sleep: Check low power idle constraints for 
> debug
> only
> 
> For SoC to achieve its lowest power platform idle state a set of hardware
> preconditions must be met. These preconditions or constraints can be
> obtained by issuing a device specific method (_DSM) with function "1".
> Refer to the document provided in the link below.
> 
> Here during initialization (from attach() callback of LPS0 device), invoke
> function 1 to get the device constraints. Each enabled constraint is
> stored in a table.
> 
> The devices in this table are used to check whether they were in required
> minimum state, while entering suspend. This check is done from platform
> freeze wake() callback, only when /sys/power/pm_debug_messages attribute
> is non zero.
> 
> If any constraint is not met and device is ACPI power managed then it
> prints the device name to kernel logs.
> 
> Also if debug is enabled in acpi/sleep.c, the constraint table and state
> of each device on wake is dumped in kernel logs.
> 
> Link:
> http://www.uefi.org/sites/default/files/resources/Intel_ACPI_Low_Power_S0_Idle.
> pdf
> Signed-off-by: Srinivas Pandruvada <srinivas.pandruv...@linux.intel.com>
> ---
>  drivers/acpi/sleep.c | 162
> +++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 162 insertions(+)
> 
> diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
> index 2b881de..b3ef577 100644
> --- a/drivers/acpi/sleep.c
> +++ b/drivers/acpi/sleep.c
> @@ -669,6 +669,7 @@ static const struct acpi_device_id lps0_device_ids[] = {
> 
>  #define ACPI_LPS0_DSM_UUID   "c4eb40a0-6cd2-11e2-bcfd-0800200c9a66"
> 
> +#define ACPI_LPS0_GET_DEVICE_CONSTRAINTS     1
>  #define ACPI_LPS0_SCREEN_OFF 3
>  #define ACPI_LPS0_SCREEN_ON  4
>  #define ACPI_LPS0_ENTRY              5
> @@ -680,6 +681,162 @@ static acpi_handle lps0_device_handle;
>  static guid_t lps0_dsm_guid;
>  static char lps0_dsm_func_mask;
> 
> +/* Device constraint entry structure */
> +struct lpi_device_info {
> +     char *name;
> +     int enabled;
> +     union acpi_object *package;
> +};
> +
> +/* Constraint package structure */
> +struct lpi_device_constraint {
> +     int uid;
> +     int min_dstate;
> +     int function_states;
> +};
> +
> +struct lpi_constraints {
> +     char *name;
> +     int min_dstate;
> +};
> +
> +static struct lpi_constraints *lpi_constraints_table;
> +static int lpi_constraints_table_size;
> +
> +static void lpi_device_get_constraints(void)
> +{
> +     union acpi_object *out_obj;
> +     int i;
> +
> +     out_obj = acpi_evaluate_dsm_typed(lps0_device_handle, &lps0_dsm_guid,
> +                                       1,
> ACPI_LPS0_GET_DEVICE_CONSTRAINTS,
> +                                       NULL, ACPI_TYPE_PACKAGE);
> +
> +     acpi_handle_debug(lps0_device_handle, "_DSM function 1 eval %s\n",
> +                       out_obj ? "successful" : "failed");
> +
> +     if (!out_obj)
> +             return;
> +
> +     lpi_constraints_table = kcalloc(out_obj->package.count,
> +                                     sizeof(*lpi_constraints_table),
> +                                     GFP_KERNEL);
> +     if (!lpi_constraints_table)
> +             goto free_acpi_buffer;
> +
> +     pr_debug("LPI: constraints dump begin\n");
> +     for (i = 0; i < out_obj->package.count; i++) {
> +             union acpi_object *package = &out_obj->package.elements[i];
> +             struct lpi_device_info info = { };
> +             int package_count = 0, j;
> +
> +             if (!package)
> +                     continue;
> +
> +             for (j = 0; j < package->package.count; ++j) {
> +                     union acpi_object *element =
> +                                     &(package->package.elements[j]);
> +
> +                     switch (element->type) {
> +                     case ACPI_TYPE_INTEGER:
> +                             info.enabled = element->integer.value;
> +                             break;
> +                     case ACPI_TYPE_STRING:
> +                             info.name = element->string.pointer;
> +                             break;
> +                     case ACPI_TYPE_PACKAGE:
> +                             package_count = element->package.count;
> +                             info.package = element->package.elements;
> +                             break;
> +                     }
> +             }
> +
> +             if (!info.enabled || !info.package || !info.name)
> +                     continue;
> +
> +             lpi_constraints_table[lpi_constraints_table_size].name =
> +                                             kstrdup(info.name, GFP_KERNEL);
> +             if (!lpi_constraints_table[lpi_constraints_table_size].name)
> +                     goto free_constraints;
> +
> +             pr_debug("index:%d Name:%s\n", i, info.name);
> +
> +             for (j = 0; j < package_count; ++j) {
> +                     union acpi_object *info_obj = &info.package[j];
> +                     union acpi_object *cnstr_pkg;
> +                     union acpi_object *obj;
> +                     struct lpi_device_constraint dev_info;
> +
> +                     switch (info_obj->type) {
> +                     case ACPI_TYPE_INTEGER:
> +                             /* version */
> +                             break;
> +                     case ACPI_TYPE_PACKAGE:
> +                             if (info_obj->package.count < 2)
> +                                     break;
> +
> +                             cnstr_pkg = info_obj->package.elements;
> +                             obj = &cnstr_pkg[0];
> +                             dev_info.uid = obj->integer.value;
> +                             obj = &cnstr_pkg[1];
> +                             dev_info.min_dstate = obj->integer.value;
> +                             pr_debug("uid %d min_dstate %d\n",
> +                                      dev_info.uid,
> +                                      dev_info.min_dstate);
> +                             lpi_constraints_table[
> +                                     lpi_constraints_table_size].min_dstate =
> +                                             dev_info.min_dstate;
> +                             break;
> +                     }
> +             }
> +
> +             lpi_constraints_table_size++;
> +     }
> +
> +     pr_debug("LPI: constraints dump end\n");
> +free_acpi_buffer:
> +     ACPI_FREE(out_obj);
> +     return;
> +
> +free_constraints:
> +     ACPI_FREE(out_obj);
> +     for (i = 0; i < lpi_constraints_table_size; ++i)
> +             kfree(lpi_constraints_table[i].name);
> +     kfree(lpi_constraints_table);
> +     lpi_constraints_table_size = 0;
> +}
> +
> +static void lpi_check_constraints(void)
> +{
> +     int i;
> +
> +     for (i = 0; i < lpi_constraints_table_size; ++i) {
> +             acpi_handle handle;
> +             struct acpi_device *adev;
> +             int state, ret;
> +
> +             if (ACPI_FAILURE(acpi_get_handle(NULL,
> +                                              lpi_constraints_table[i].name,
> +                                              &handle)))
> +                     continue;
> +
> +             if (acpi_bus_get_device(handle, &adev))
> +                     continue;
> +
> +             ret = acpi_device_get_power(adev, &state);
> +             if (!ret)
> +                     pr_debug("LPI: %s required min power state %d, current
> power state %d, real power state %d\n",
> +                              lpi_constraints_table[i].name,
> +                              lpi_constraints_table[i].min_dstate,
> +                              adev->power.state, state);
Isn't this superfluous to be showing the state returned from 
acpi_device_get_power and
also probing directly at the state? You can't just rely on the information you 
got
back from apci_device_get_power?

> +
> +             if (adev->flags.power_manageable && adev->power.state <
> +                                     lpi_constraints_table[i].min_dstate)
> +                     pr_info("LPI: Constraint [%s] not matched\n",
> +                              lpi_constraints_table[i].name);
Similarly here, can't you just compare against &state instead?

> +     }
> +}
> +
>  static void acpi_sleep_run_lps0_dsm(unsigned int func)
>  {
>       union acpi_object *out_obj;
> @@ -729,6 +886,9 @@ static int lps0_device_attach(struct acpi_device *adev,
>                                 "_DSM function 0 evaluation failed\n");
>       }
>       ACPI_FREE(out_obj);
> +
> +     lpi_device_get_constraints();
> +
>       return 0;
>  }
> 
> @@ -773,6 +933,8 @@ static void acpi_freeze_wake(void)
>        */
>       if (acpi_sci_irq_valid() &&
>           !irqd_is_wakeup_armed(irq_get_irq_data(acpi_sci_irq))) {
> +             if (pm_debug_messages_enabled())
> +                     lpi_check_constraints();
>               pm_system_cancel_wakeup();
>               s2idle_wakeup = true;
>       }
> --
> 2.7.5

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