[SRU][N][PATCH 1/3] UBUNTU: SAUCE: PCI: vmd: Set PCI devices to D0 before enable PCI PM's L1 substates

[En-Wei Wu]

From: Jian-Hong Pan <jhp at endlessos.org>

BugLink: https://bugs.launchpad.net/bugs/2085092

The remapped PCIe Root Port and the child device have PCI PM L1 substates
capability, but they are disabled originally.

Here is a failed example on ASUS B1400CEAE:

Capabilities: [900 v1] L1 PM Substates
	L1SubCap: PCI-PM_L1.2+ PCI-PM_L1.1- ASPM_L1.2+ ASPM_L1.1- L1_PM_Substates+
		  PortCommonModeRestoreTime=32us PortTPowerOnTime=10us
	L1SubCtl1: PCI-PM_L1.2- PCI-PM_L1.1- ASPM_L1.2+ ASPM_L1.1-
		   T_CommonMode=0us LTR1.2_Threshold=101376ns
	L1SubCtl2: T_PwrOn=50us

Power on all of the VMD remapped PCI devices to D0 before enable PCI-PM L1
PM Substates by following "PCIe r6.0, sec 5.5.4".

Link: https://bugzilla.kernel.org/show_bug.cgi?id=218394
Signed-off-by: Jian-Hong Pan <jhp at endlessos.org>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy at linux.intel.com>
(backported from https://lore.kernel.org/linux-pci/20241001083438.10070-2-jhp@endlessos.org)
[En-Wei - need to fix this issue ASAP and the patch hasn't been merged yet]
Signed-off-by: En-Wei Wu <en-wei.wu at canonical.com>
---
 drivers/pci/controller/vmd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index e5a0c6c57524..732bc3b7e69f 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -750,7 +750,7 @@ static int vmd_pm_enable_quirk(struct pci_dev *pdev, void *userdata)
 
 	if (!(features & VMD_FEAT_BIOS_PM_QUIRK))
 		return 0;
-
+	
 	pdev->aspm_os_control = 1;
 
 	pci_enable_link_state_locked(pdev, PCIE_LINK_STATE_ALL);
-- 
2.43.0