[PATCH v2 2/4] PCI/ASPM: Add pcie_aspm_remove_cap() to override advertised link states

[Bjorn Helgaas]

From: Bjorn Helgaas <bhelgaas at google.com>

Add pcie_aspm_remove_cap().  A quirk can use this to prevent use of ASPM
L0s or L1 link states, even if the device advertised support for them.

Signed-off-by: Bjorn Helgaas <bhelgaas at google.com>
---
 drivers/pci/pci.h       |  2 ++
 drivers/pci/pcie/aspm.c | 13 +++++++++++++
 2 files changed, 15 insertions(+)

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 4492b809094b..36f8c0985430 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -958,6 +958,7 @@ void pci_save_aspm_l1ss_state(struct pci_dev *dev);
 void pci_restore_aspm_l1ss_state(struct pci_dev *dev);
 
 #ifdef CONFIG_PCIEASPM
+void pcie_aspm_remove_cap(struct pci_dev *pdev, u32 lnkcap);
 void pcie_aspm_init_link_state(struct pci_dev *pdev);
 void pcie_aspm_exit_link_state(struct pci_dev *pdev);
 void pcie_aspm_pm_state_change(struct pci_dev *pdev, bool locked);
@@ -965,6 +966,7 @@ void pcie_aspm_powersave_config_link(struct pci_dev *pdev);
 void pci_configure_ltr(struct pci_dev *pdev);
 void pci_bridge_reconfigure_ltr(struct pci_dev *pdev);
 #else
+static inline void pcie_aspm_remove_cap(struct pci_dev *pdev, u32 lnkcap) { }
 static inline void pcie_aspm_init_link_state(struct pci_dev *pdev) { }
 static inline void pcie_aspm_exit_link_state(struct pci_dev *pdev) { }
 static inline void pcie_aspm_pm_state_change(struct pci_dev *pdev, bool locked) { }
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 15d50c089070..bc3cb8bc7018 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -1542,6 +1542,19 @@ int pci_enable_link_state_locked(struct pci_dev *pdev, int state)
 }
 EXPORT_SYMBOL(pci_enable_link_state_locked);
 
+void pcie_aspm_remove_cap(struct pci_dev *pdev, u32 lnkcap)
+{
+	if (lnkcap & PCI_EXP_LNKCAP_ASPM_L0S)
+		pdev->aspm_l0s_support = 0;
+	if (lnkcap & PCI_EXP_LNKCAP_ASPM_L1)
+		pdev->aspm_l1_support = 0;
+
+	pci_info(pdev, "ASPM:%s%s removed from Link Capabilities to avoid device defect\n",
+		 lnkcap & PCI_EXP_LNKCAP_ASPM_L0S ? " L0s" : "",
+		 lnkcap & PCI_EXP_LNKCAP_ASPM_L1 ? " L1" : "");
+
+}
+
 static int pcie_aspm_set_policy(const char *val,
 				const struct kernel_param *kp)
 {
-- 
2.43.0