From 6e332df7c380a7bc936275cba1ed356d9eb36b39 Mon Sep 17 00:00:00 2001 From: "Saheed O. Bolarinwa" Date: Fri, 19 Nov 2021 20:37:31 +0100 Subject: [PATCH] PCI/ASPM: Stop caching device L0s, L1 acceptable exit latencies Previously we calculated the device's acceptable L0s and L1 exit latencies in pcie_aspm_cap_init() and cached them in struct pcie_link_state. These values are only used in pcie_aspm_check_latency() where they are compared with the actual exit latencies of the link. This path is used when removing or changing the D state of the device, so it's relatively low frequency. To reduce the amount of per-link data we store, remove the acceptable[] arrays from struct pcie_link_state and calculate them directly from the already-cached Device Capabilities register when needed. [bhelgaas: use endpoint->devcap instead of reading it again] Link: https://lore.kernel.org/r/20211119193732.12343-4-refactormyself@gmail.com Signed-off-by: Saheed O. Bolarinwa Signed-off-by: Bjorn Helgaas --- drivers/pci/pcie/aspm.c | 29 ++++++++++------------------- 1 file changed, 10 insertions(+), 19 deletions(-) diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c index a7a1d59c338f..9faefb4d3378 100644 --- a/drivers/pci/pcie/aspm.c +++ b/drivers/pci/pcie/aspm.c @@ -65,12 +65,6 @@ struct pcie_link_state { u32 clkpm_enabled:1; /* Current Clock PM state */ u32 clkpm_default:1; /* Default Clock PM state by BIOS */ u32 clkpm_disable:1; /* Clock PM disabled */ - - /* - * Endpoint acceptable latencies. A pcie downstream port only - * has one slot under it, so at most there are 8 functions. - */ - struct aspm_latency acceptable[8]; }; static int aspm_disabled, aspm_force; @@ -389,7 +383,8 @@ static void encode_l12_threshold(u32 threshold_us, u32 *scale, u32 *value) static void pcie_aspm_check_latency(struct pci_dev *endpoint) { - u32 latency, lnkcap_up, lnkcap_dw, l1_switch_latency = 0; + u32 latency, encoding, lnkcap_up, lnkcap_dw; + u32 l1_switch_latency = 0; struct aspm_latency latency_up, latency_dw; struct aspm_latency *acceptable; struct pcie_link_state *link; @@ -400,7 +395,14 @@ static void pcie_aspm_check_latency(struct pci_dev *endpoint) return; link = endpoint->bus->self->link_state; - acceptable = &link->acceptable[PCI_FUNC(endpoint->devfn)]; + + /* Calculate endpoint L0s acceptable latency */ + encoding = (endpoint->devcap & PCI_EXP_DEVCAP_L0S) >> 6; + acceptable->l0s = calc_l0s_acceptable(encoding); + + /* Calculate endpoint L1 acceptable latency */ + encoding = (endpoint->devcap & PCI_EXP_DEVCAP_L1) >> 9; + acceptable->l1 = calc_l1_acceptable(encoding); while (link) { struct pci_dev *dev = pci_function_0(link->pdev->subordinate); @@ -666,22 +668,11 @@ static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist) /* Get and check endpoint acceptable latencies */ list_for_each_entry(child, &linkbus->devices, bus_list) { - u32 reg32, encoding; - struct aspm_latency *acceptable = - &link->acceptable[PCI_FUNC(child->devfn)]; if (pci_pcie_type(child) != PCI_EXP_TYPE_ENDPOINT && pci_pcie_type(child) != PCI_EXP_TYPE_LEG_END) continue; - pcie_capability_read_dword(child, PCI_EXP_DEVCAP, ®32); - /* Calculate endpoint L0s acceptable latency */ - encoding = (reg32 & PCI_EXP_DEVCAP_L0S) >> 6; - acceptable->l0s = calc_l0s_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); } }