From 07d92760d2ee542fe932f4e8b5807dd98481d1fd Mon Sep 17 00:00:00 2001 From: Kenji Kaneshige Date: Wed, 19 Aug 2009 11:00:25 +0900 Subject: [PATCH] PCI ASPM: introduce capable flag 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. Acked-by: Shaohua Li Signed-off-by: Kenji Kaneshige Signed-off-by: Jesse Barnes --- drivers/pci/pcie/aspm.c | 117 +++++++++++++++++++++++++++++----------- 1 file changed, 86 insertions(+), 31 deletions(-) diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c index 8f7884a8bc2e..79f6d61798fa 100644 --- a/drivers/pci/pcie/aspm.c +++ b/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(struct pci_dev *pdev, u32 *state, *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 pcie_link_state *link, int blacklist) /* 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 pcie_link_state *link, int blacklist) 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 pcie_link_state *link, int blacklist) */ 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 pci_dev *pdev) 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 pci_dev *pdev) 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); } /* -- 2.30.2