Usually the most accurate way to determine a PCI device's power state is
to read its PM Control & Status Register. There are two cases however
when this is not an option: If the device doesn't have the PM
capability at all, or if it is in D3cold.
In D3cold, reading from config space typically results in a fabricated
"all ones" response. But in D3hot, the two bits representing the power
state in the PMCSR are *also* set to 1. Thus D3hot and D3cold are not
discernible by just reading the PMCSR.
A (supposedly) reliable way to detect D3cold is to query the platform
firmware for its opinion on the device's power state. To this end,
add a ->get_power callback to struct pci_platform_pm_ops, and an
implementation to acpi_pci_platform_pm. (The only pci_platform_pm_ops
existing so far).
Amend pci_update_current_state() to query the platform firmware before
reading the PMCSR.
Cc: Rafael J. Wysocki <rjw@xxxxxxxxxxxxx>
Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
---
drivers/pci/pci-acpi.c | 23 +++++++++++++++++++++++
drivers/pci/pci.c | 21 ++++++++++++++++-----
drivers/pci/pci.h | 3 +++
3 files changed, 42 insertions(+), 5 deletions(-)
diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index 9a033e8..89f2707 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -452,6 +452,28 @@ static int acpi_pci_set_power_state(struct pci_dev *dev, pci_power_t state)
return error;
}
+static pci_power_t acpi_pci_get_power_state(struct pci_dev *dev)
+{
+ struct acpi_device *adev = ACPI_COMPANION(&dev->dev);
+ static const pci_power_t state_conv[] = {
+ [ACPI_STATE_D0] = PCI_D0,
+ [ACPI_STATE_D1] = PCI_D1,
+ [ACPI_STATE_D2] = PCI_D2,
+ [ACPI_STATE_D3_HOT] = PCI_D3hot,
+ [ACPI_STATE_D3_COLD] = PCI_D3cold,
+ };
+ int state;
+
+ if (!adev || !acpi_device_power_manageable(adev))
+ return PCI_UNKNOWN;
+
+ if (acpi_device_get_power(adev, &state) || state < ACPI_STATE_D0
+ || state > ACPI_STATE_D3_COLD)
+ return PCI_UNKNOWN;
+
+ return state_conv[state];
+}
+
static bool acpi_pci_can_wakeup(struct pci_dev *dev)
{
struct acpi_device *adev = ACPI_COMPANION(&dev->dev);
@@ -534,6 +556,7 @@ static bool acpi_pci_need_resume(struct pci_dev *dev)
static const struct pci_platform_pm_ops acpi_pci_platform_pm = {
.is_manageable = acpi_pci_power_manageable,
.set_state = acpi_pci_set_power_state,
+ .get_state = acpi_pci_get_power_state,
.choose_state = acpi_pci_choose_state,
.sleep_wake = acpi_pci_sleep_wake,
.run_wake = acpi_pci_run_wake,
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 72a9d3a..e52e3d4 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -552,8 +552,9 @@ static const struct pci_platform_pm_ops *pci_platform_pm;
int pci_set_platform_pm(const struct pci_platform_pm_ops *ops)
{
- if (!ops->is_manageable || !ops->set_state || !ops->choose_state ||
- !ops->sleep_wake || !ops->run_wake || !ops->need_resume)
+ if (!ops->is_manageable || !ops->set_state || !ops->get_state ||
+ !ops->choose_state || !ops->sleep_wake || !ops->run_wake ||
+ !ops->need_resume)
return -EINVAL;
pci_platform_pm = ops;
return 0;
@@ -570,6 +571,11 @@ static inline int platform_pci_set_power_state(struct pci_dev *dev,
return pci_platform_pm ? pci_platform_pm->set_state(dev, t) : -ENOSYS;
}
+static inline pci_power_t platform_pci_get_power_state(struct pci_dev *dev)
+{
+ return pci_platform_pm ? pci_platform_pm->get_state(dev) : PCI_UNKNOWN;
+}
+
static inline pci_power_t platform_pci_choose_state(struct pci_dev *dev)
{
return pci_platform_pm ?
@@ -701,14 +707,19 @@ static int pci_raw_set_power_state(struct pci_dev *dev, pci_power_t state)
}
/**
- * pci_update_current_state - Read PCI power state of given device from its
- * PCI PM registers and cache it
+ * pci_update_current_state - Read power state of given device and cache it
* @dev: PCI device to handle.
* @state: State to cache in case the device doesn't have the PM capability
+ *
+ * The power state is read from the PMCSR register, which however is
+ * inaccessible in D3cold. The platform firmware is therefore queried first
+ * to detect accessibility of the register.
*/
void pci_update_current_state(struct pci_dev *dev, pci_power_t state)
{
- if (dev->pm_cap) {
+ if (platform_pci_get_power_state(dev) == PCI_D3cold) {
+ dev->current_state = PCI_D3cold;
+ } else if (dev->pm_cap) {
u16 pmcsr;
/*
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 9730c47..01d5206 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -42,6 +42,8 @@ int pci_probe_reset_function(struct pci_dev *dev);
*
* @set_state: invokes the platform firmware to set the device's power state
*
+ * @get_state: queries the platform firmware for a device's current power state
+ *
* @choose_state: returns PCI power state of given device preferred by the
* platform; to be used during system-wide transitions from a
* sleeping state to the working state and vice versa
@@ -62,6 +64,7 @@ int pci_probe_reset_function(struct pci_dev *dev);
struct pci_platform_pm_ops {
bool (*is_manageable)(struct pci_dev *dev);
int (*set_state)(struct pci_dev *dev, pci_power_t state);
+ pci_power_t (*get_state)(struct pci_dev *dev);
pci_power_t (*choose_state)(struct pci_dev *dev);
int (*sleep_wake)(struct pci_dev *dev, bool enable);
int (*run_wake)(struct pci_dev *dev, bool enable);
--
2.8.1
--
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