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Date: Thu, 10 Aug 2017 22:07:15 +0000
From: <Mario.Limonciello@...l.com>
To: <srinivas.pandruvada@...ux.intel.com>, <rjw@...ysocki.net>,
<lenb@...nel.org>
CC: <linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<linux-acpi@...r.kernel.org>, <lukas@...ner.de>
Subject: RE: [PATCH v2 2/2] ACPI / Sleep: Check low power idle constraints for
debug only
> -----Original Message-----
> From: Srinivas Pandruvada [mailto:srinivas.pandruvada@...ux.intel.com]
> Sent: Tuesday, August 8, 2017 5:41 PM
> To: rjw@...ysocki.net; lenb@...nel.org
> Cc: linux-pm@...r.kernel.org; Limonciello, Mario <Mario_Limonciello@...l.com>;
> linux-kernel@...r.kernel.org; linux-acpi@...r.kernel.org; lukas@...ner.de;
> Srinivas Pandruvada <srinivas.pandruvada@...ux.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.pandruvada@...ux.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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