[PATCH 2/2][SRU][J][K][OEM-5.14][OEM-5.17] PCI:ASPM: Remove pcie_aspm_pm_state_change()

[AceLan Kao]

From: Kai-Heng Feng <kai.heng.feng at canonical.com>

BugLink: https://bugs.launchpad.net/bugs/1980829

pcie_aspm_pm_state_change() was introduced at the inception of PCIe
ASPM code.

However, it can cause some issues. For instance, when ASPM config is
changed via sysfs, those changes won't persist across power state change
because pcie_aspm_pm_state_change() overwrites them.

In addition to that, if the driver is to restore L1ss [1] after system
resume, the restored states will also be overwritten by
pcie_aspm_pm_state_change().

So remove pcie_aspm_pm_state_change() for now, if there's any hardware
really needs it to function, a quirk can be used instead.

[1] https://lore.kernel.org/linux-pci/20220201123536.12962-1-vidyas@nvidia.com/

Signed-off-by: Kai-Heng Feng <kai.heng.feng at canonical.com>
(cherry picked from commit https://patchwork.ozlabs.org/project/linux-pci/patch/20220509073639.2048236-1-kai.heng.feng@canonical.com/)
Signed-off-by: Chia-Lin Kao (AceLan) <acelan.kao at canonical.com>
---
 drivers/pci/pci.c       |  3 ---
 drivers/pci/pci.h       |  2 --
 drivers/pci/pcie/aspm.c | 19 -------------------
 3 files changed, 24 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index af3740bc81d47..2579fb3824301 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1133,9 +1133,6 @@ static int pci_raw_set_power_state(struct pci_dev *dev, pci_power_t state)
 	if (need_restore)
 		pci_restore_bars(dev);
 
-	if (dev->bus->self)
-		pcie_aspm_pm_state_change(dev->bus->self);
-
 	return 0;
 }
 
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 1edff498aeaa9..9c15e70466c74 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -579,14 +579,12 @@ bool pcie_wait_for_link(struct pci_dev *pdev, bool active);
 #ifdef CONFIG_PCIEASPM
 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);
 void pcie_aspm_powersave_config_link(struct pci_dev *pdev);
 void pci_save_aspm_l1ss_state(struct pci_dev *dev);
 void pci_restore_aspm_l1ss_state(struct pci_dev *dev);
 #else
 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) { }
 static inline void pcie_aspm_powersave_config_link(struct pci_dev *pdev) { }
 static inline void pci_save_aspm_l1ss_state(struct pci_dev *dev) { }
 static inline void pci_restore_aspm_l1ss_state(struct pci_dev *dev) { }
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 09987b8023c9d..dcd7565d0e96f 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -1065,25 +1065,6 @@ void pcie_aspm_exit_link_state(struct pci_dev *pdev)
 	up_read(&pci_bus_sem);
 }
 
-/* @pdev: the root port or switch downstream port */
-void pcie_aspm_pm_state_change(struct pci_dev *pdev)
-{
-	struct pcie_link_state *link = pdev->link_state;
-
-	if (aspm_disabled || !link)
-		return;
-	/*
-	 * Devices changed PM state, we should recheck if latency
-	 * meets all functions' requirement
-	 */
-	down_read(&pci_bus_sem);
-	mutex_lock(&aspm_lock);
-	pcie_update_aspm_capable(link->root);
-	pcie_config_aspm_path(link);
-	mutex_unlock(&aspm_lock);
-	up_read(&pci_bus_sem);
-}
-
 void pcie_aspm_powersave_config_link(struct pci_dev *pdev)
 {
 	struct pcie_link_state *link = pdev->link_state;
-- 
2.25.1