summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorAaron Lu <aaron.lu@intel.com>2015-03-25 14:37:06 +0800
committerBjorn Helgaas <bhelgaas@google.com>2015-04-08 16:25:25 -0500
commite33caa82e221b0bbeba373b507e3f134dc2efa1a (patch)
tree5a5b5cb497a21c0342ac0a7d2956b366020fef68
parent3390e0850b711d163b35508464cfbe0a4477dfe2 (diff)
downloadop-kernel-dev-e33caa82e221b0bbeba373b507e3f134dc2efa1a.zip
op-kernel-dev-e33caa82e221b0bbeba373b507e3f134dc2efa1a.tar.gz
PCI/ACPI: Optimize device state transition delays
The PCI "ACPI additions for FW latency optimizations" ECN (link below) defines two functions in the PCI _DSM: Function 8, "Reset Delay," applies to the entire hierarchy below a PCI host bridge. If it returns one, the OS may assume that all devices in the hierarchy have already completed power-on reset delays. Function 9, "Device Readiness Durations," applies only to the object where it is located. It returns delay durations required after various events if the device requires less time than the spec requires. Delays from this function take precedence over the Reset Delay function. Add support for Reset Delay and part of Device Readiness Durations. [bhelgaas: changelog, comments] Link: https://www.pcisig.com/specifications/conventional/pci_firmware/ECN_fw_latency_optimization_final.pdf Signed-off-by: Aaron Lu <aaron.lu@intel.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
-rw-r--r--drivers/pci/pci-acpi.c74
-rw-r--r--include/linux/pci-acpi.h2
-rw-r--r--include/linux/pci.h1
3 files changed, 77 insertions, 0 deletions
diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index bea6be4..5eba747 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -537,11 +537,32 @@ static struct pci_platform_pm_ops acpi_pci_platform_pm = {
void acpi_pci_add_bus(struct pci_bus *bus)
{
+ union acpi_object *obj;
+ struct pci_host_bridge *bridge;
+
if (acpi_pci_disabled || !bus->bridge)
return;
acpi_pci_slot_enumerate(bus);
acpiphp_enumerate_slots(bus);
+
+ /*
+ * For a host bridge, check its _DSM for function 8 and if
+ * that is available, mark it in pci_host_bridge.
+ */
+ if (!pci_is_root_bus(bus))
+ return;
+
+ obj = acpi_evaluate_dsm(ACPI_HANDLE(bus->bridge), pci_acpi_dsm_uuid, 3,
+ RESET_DELAY_DSM, NULL);
+ if (!obj)
+ return;
+
+ if (obj->type == ACPI_TYPE_INTEGER && obj->integer.value == 1) {
+ bridge = pci_find_host_bridge(bus);
+ bridge->ignore_reset_delay = 1;
+ }
+ ACPI_FREE(obj);
}
void acpi_pci_remove_bus(struct pci_bus *bus)
@@ -567,6 +588,57 @@ static struct acpi_device *acpi_pci_find_companion(struct device *dev)
check_children);
}
+/**
+ * pci_acpi_optimize_delay - optimize PCI D3 and D3cold delay from ACPI
+ * @pdev: the PCI device whose delay is to be updated
+ * @adev: the companion ACPI device of this PCI device
+ *
+ * Update the d3_delay and d3cold_delay of a PCI device from the ACPI _DSM
+ * control method of either the device itself or the PCI host bridge.
+ *
+ * Function 8, "Reset Delay," applies to the entire hierarchy below a PCI
+ * host bridge. If it returns one, the OS may assume that all devices in
+ * the hierarchy have already completed power-on reset delays.
+ *
+ * Function 9, "Device Readiness Durations," applies only to the object
+ * where it is located. It returns delay durations required after various
+ * events if the device requires less time than the spec requires. Delays
+ * from this function take precedence over the Reset Delay function.
+ *
+ * These _DSM functions are defined by the draft ECN of January 28, 2014,
+ * titled "ACPI additions for FW latency optimizations."
+ */
+static void pci_acpi_optimize_delay(struct pci_dev *pdev,
+ acpi_handle handle)
+{
+ struct pci_host_bridge *bridge = pci_find_host_bridge(pdev->bus);
+ int value;
+ union acpi_object *obj, *elements;
+
+ if (bridge->ignore_reset_delay)
+ pdev->d3cold_delay = 0;
+
+ obj = acpi_evaluate_dsm(handle, pci_acpi_dsm_uuid, 3,
+ FUNCTION_DELAY_DSM, NULL);
+ if (!obj)
+ return;
+
+ if (obj->type == ACPI_TYPE_PACKAGE && obj->package.count == 5) {
+ elements = obj->package.elements;
+ if (elements[0].type == ACPI_TYPE_INTEGER) {
+ value = (int)elements[0].integer.value / 1000;
+ if (value < PCI_PM_D3COLD_WAIT)
+ pdev->d3cold_delay = value;
+ }
+ if (elements[3].type == ACPI_TYPE_INTEGER) {
+ value = (int)elements[3].integer.value / 1000;
+ if (value < PCI_PM_D3_WAIT)
+ pdev->d3_delay = value;
+ }
+ }
+ ACPI_FREE(obj);
+}
+
static void pci_acpi_setup(struct device *dev)
{
struct pci_dev *pci_dev = to_pci_dev(dev);
@@ -575,6 +647,8 @@ static void pci_acpi_setup(struct device *dev)
if (!adev)
return;
+ pci_acpi_optimize_delay(pci_dev, adev->handle);
+
pci_acpi_add_pm_notifier(adev, pci_dev);
if (!adev->wakeup.flags.valid)
return;
diff --git a/include/linux/pci-acpi.h b/include/linux/pci-acpi.h
index 3801c70..a965efa 100644
--- a/include/linux/pci-acpi.h
+++ b/include/linux/pci-acpi.h
@@ -79,6 +79,8 @@ static inline void acpiphp_check_host_bridge(struct acpi_device *adev) { }
extern const u8 pci_acpi_dsm_uuid[];
#define DEVICE_LABEL_DSM 0x07
+#define RESET_DELAY_DSM 0x08
+#define FUNCTION_DELAY_DSM 0x09
#else /* CONFIG_ACPI */
static inline void acpi_pci_add_bus(struct pci_bus *bus) { }
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 211e9da..c5aa7b8 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -406,6 +406,7 @@ struct pci_host_bridge {
struct list_head windows; /* resource_entry */
void (*release_fn)(struct pci_host_bridge *);
void *release_data;
+ unsigned int ignore_reset_delay:1; /* for entire hierarchy */
};
#define to_pci_host_bridge(n) container_of(n, struct pci_host_bridge, dev)
OpenPOWER on IntegriCloud