Introduce 'aspm_capable' field to maintain the capable ASPM setting of
the link. By the 'aspm_capable', we don't need to recheck latency
every time ASPM policy is changed.
Each bit in 'aspm_capable' is associated to ASPM state (L0S/L1). The
bit is set if the associated ASPM state is supported by the link and
it satisfies the latency requirement (i.e. exit latency < endpoint
acceptable latency). The 'aspm_capable' is updated when
- an endpoint device is added (boot time or hot-plug time)
- an endpoint device is removed (hot-unplug time)
- PCI power state is changed.
Signed-off-by: Kenji Kaneshige <kaneshige.kenji@xxxxxxxxxxxxxx>
---
drivers/pci/pcie/aspm.c | 117 +++++++++++++++++++++++++++++++++++-------------
1 file changed, 86 insertions(+), 31 deletions(-)
Index: 20090818/drivers/pci/pcie/aspm.c
===================================================================
--- 20090818.orig/drivers/pci/pcie/aspm.c
+++ 20090818/drivers/pci/pcie/aspm.c
@@ -42,6 +42,7 @@ struct pcie_link_state {
/* ASPM state */
u32 aspm_support:2; /* Supported ASPM state */
u32 aspm_enabled:2; /* Enabled ASPM state */
+ u32 aspm_capable:2; /* Capable ASPM state with latency */
u32 aspm_default:2; /* Default ASPM state by BIOS */
u32 aspm_disable:2; /* Disabled ASPM state */
@@ -316,6 +317,39 @@ static void pcie_aspm_get_cap_device(str
*enabled = reg16 & (PCIE_LINK_STATE_L0S | PCIE_LINK_STATE_L1);
}
+static void pcie_aspm_check_latency(struct pci_dev *endpoint)
+{
+ u32 l1_switch_latency = 0;
+ struct aspm_latency *acceptable;
+ struct pcie_link_state *link;
+
+ /* Device not in D0 doesn't need latency check */
+ if ((endpoint->current_state != PCI_D0) &&
+ (endpoint->current_state != PCI_UNKNOWN))
+ return;
+
+ link = endpoint->bus->self->link_state;
+ acceptable = &link->acceptable[PCI_FUNC(endpoint->devfn)];
+
+ while (link) {
+ /* Check L0s latency */
+ if ((link->aspm_capable & PCIE_LINK_STATE_L0S) &&
+ (link->latency.l0s > acceptable->l0s))
+ link->aspm_capable &= ~PCIE_LINK_STATE_L0S;
+ /*
+ * Check L1 latency.
+ * Every switch on the path to root complex need 1
+ * more microsecond for L1. Spec doesn't mention L0s.
+ */
+ if ((link->aspm_capable & PCIE_LINK_STATE_L1) &&
+ (link->latency.l1 + l1_switch_latency > acceptable->l1))
+ link->aspm_capable &= ~PCIE_LINK_STATE_L1;
+ l1_switch_latency += 1000;
+
+ link = link->parent;
+ }
+}
+
static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)
{
u32 support, l0s, l1, enabled;
@@ -348,6 +382,9 @@ static void pcie_aspm_cap_init(struct pc
/* Save default state */
link->aspm_default = link->aspm_enabled;
+
+ /* Setup initial capable state. Will be updated later */
+ link->aspm_capable = link->aspm_support;
/*
* If the downstream component has pci bridge function, don't
* do ASPM for now.
@@ -376,12 +413,14 @@ static void pcie_aspm_cap_init(struct pc
pos = pci_find_capability(child, PCI_CAP_ID_EXP);
pci_read_config_dword(child, pos + PCI_EXP_DEVCAP, ®32);
+ /* Calculate endpoint L0s acceptable latency */
encoding = (reg32 & PCI_EXP_DEVCAP_L0S) >> 6;
acceptable->l0s = calc_l0s_acceptable(encoding);
- if (link->aspm_support & PCIE_LINK_STATE_L1) {
- encoding = (reg32 & PCI_EXP_DEVCAP_L1) >> 9;
- acceptable->l1 = calc_l1_acceptable(encoding);
- }
+ /* Calculate endpoint L1 acceptable latency */
+ encoding = (reg32 & PCI_EXP_DEVCAP_L1) >> 9;
+ acceptable->l1 = calc_l1_acceptable(encoding);
+
+ pcie_aspm_check_latency(child);
}
}
@@ -397,27 +436,10 @@ static void pcie_aspm_cap_init(struct pc
*/
static u32 __pcie_aspm_check_state_one(struct pci_dev *endpoint, u32 state)
{
- u32 l1_switch_latency = 0;
- struct aspm_latency *acceptable;
- struct pcie_link_state *link;
-
- link = endpoint->bus->self->link_state;
- state &= link->aspm_support;
- acceptable = &link->acceptable[PCI_FUNC(endpoint->devfn)];
-
+ struct pcie_link_state *link = endpoint->bus->self->link_state;
while (link && state) {
- if ((state & PCIE_LINK_STATE_L0S) &&
- (link->latency.l0s > acceptable->l0s))
- state &= ~PCIE_LINK_STATE_L0S;
- if ((state & PCIE_LINK_STATE_L1) &&
- (link->latency.l1 + l1_switch_latency > acceptable->l1))
- state &= ~PCIE_LINK_STATE_L1;
+ state &= link->aspm_capable;
link = link->parent;
- /*
- * Every switch on the path to root complex need 1
- * more microsecond for L1. Spec doesn't mention L0s.
- */
- l1_switch_latency += 1000;
}
return state;
}
@@ -668,11 +690,35 @@ out:
up_read(&pci_bus_sem);
}
+/* Recheck latencies and update aspm_capable for links under the root */
+static void pcie_update_aspm_capable(struct pcie_link_state *root)
+{
+ struct pcie_link_state *link;
+ BUG_ON(root->parent);
+ list_for_each_entry(link, &link_list, sibling) {
+ if (link->root != root)
+ continue;
+ link->aspm_capable = link->aspm_support;
+ }
+ list_for_each_entry(link, &link_list, sibling) {
+ struct pci_dev *child;
+ struct pci_bus *linkbus = link->pdev->subordinate;
+ if (link->root != root)
+ continue;
+ list_for_each_entry(child, &linkbus->devices, bus_list) {
+ if ((child->pcie_type != PCI_EXP_TYPE_ENDPOINT) &&
+ (child->pcie_type != PCI_EXP_TYPE_LEG_END))
+ continue;
+ pcie_aspm_check_latency(child);
+ }
+ }
+}
+
/* @pdev: the endpoint device */
void pcie_aspm_exit_link_state(struct pci_dev *pdev)
{
struct pci_dev *parent = pdev->bus->self;
- struct pcie_link_state *link;
+ struct pcie_link_state *link, *root;
if (aspm_disabled || !pdev->is_pcie || !parent || !parent->link_state)
return;
@@ -690,6 +736,7 @@ void pcie_aspm_exit_link_state(struct pc
goto out;
link = parent->link_state;
+ root = link->root;
/* All functions are removed, so just disable ASPM for the link */
__pcie_aspm_config_one_dev(parent, 0);
@@ -697,6 +744,9 @@ void pcie_aspm_exit_link_state(struct pc
list_del(&link->link);
/* Clock PM is for endpoint device */
free_link_state(link);
+
+ /* Recheck latencies and configure upstream links */
+ pcie_update_aspm_capable(root);
out:
mutex_unlock(&aspm_lock);
up_read(&pci_bus_sem);
@@ -705,18 +755,23 @@ out:
/* @pdev: the root port or switch downstream port */
void pcie_aspm_pm_state_change(struct pci_dev *pdev)
{
- struct pcie_link_state *link_state = pdev->link_state;
+ struct pcie_link_state *link = pdev->link_state;
- if (aspm_disabled || !pdev->is_pcie || !pdev->link_state)
+ if (aspm_disabled || !pdev->is_pcie || !link)
return;
- if (pdev->pcie_type != PCI_EXP_TYPE_ROOT_PORT &&
- pdev->pcie_type != PCI_EXP_TYPE_DOWNSTREAM)
+ if ((pdev->pcie_type != PCI_EXP_TYPE_ROOT_PORT) &&
+ (pdev->pcie_type != PCI_EXP_TYPE_DOWNSTREAM))
return;
/*
- * devices changed PM state, we should recheck if latency meets all
- * functions' requirement
+ * Devices changed PM state, we should recheck if latency
+ * meets all functions' requirement
*/
- pcie_aspm_configure_link_state(link_state, link_state->aspm_enabled);
+ down_read(&pci_bus_sem);
+ mutex_lock(&aspm_lock);
+ pcie_update_aspm_capable(link->root);
+ __pcie_aspm_configure_link_state(link, link->aspm_enabled);
+ mutex_unlock(&aspm_lock);
+ up_read(&pci_bus_sem);
}
/*
--
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