linux-kernel - [PATCH v3 3/3] PCI/ASPM: Fix L1SS parameters & only enable supported features when enable link state

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Date: Wed,  7 Feb 2024 19:18:55 +0800
From: Jian-Hong Pan <jhp@...lessos.org>
To: Bjorn Helgaas <helgaas@...nel.org>,
	Johan Hovold <johan@...nel.org>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
	David Box <david.e.box@...ux.intel.com>
Cc: Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Nirmal Patel <nirmal.patel@...ux.intel.com>,
	Jonathan Derrick <jonathan.derrick@...ux.dev>,
	linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux@...lessos.org,
	Jian-Hong Pan <jhp@...lessos.org>
Subject: [PATCH v3 3/3] PCI/ASPM: Fix L1SS parameters & only enable supported features when enable link state

The original __pci_enable_link_state() configs the links directly without:
* Check the L1 substates features which are supported, or not
* Calculate & program related parameters for L1.2, such as T_POWER_ON,
  Common_Mode_Restore_Time, and LTR_L1.2_THRESHOLD

This leads some supported L1 PM substates of the link between VMD remapped
PCIe Root Port and NVMe get wrong configs when a caller tries to enabled
them.

Here is a failed example on ASUS B1400CEAE with enabled VMD:

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=0ns
        L1SubCtl2: T_PwrOn=10us

This patch initializes the link's L1 PM substates to get the supported
features and programs relating paramters, if some of them are going to be
enabled in __pci_enable_link_state(). Then, enables the L1 PM substates if
the caller intends to enable them and they are supported.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=218394
Signed-off-by: Jian-Hong Pan <jhp@...lessos.org>
---
v2:
- Prepare the PCIe LTR parameters before enable L1 Substates

v3:
- Only enable supported features for the L1 Substates part

 drivers/pci/pcie/aspm.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index a39d2ee744cb..c866971cae70 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -1389,14 +1389,16 @@ static int __pci_enable_link_state(struct pci_dev *pdev, int state, bool locked)
 		link->aspm_default |= ASPM_STATE_L0S;
 	if (state & PCIE_LINK_STATE_L1)
 		link->aspm_default |= ASPM_STATE_L1;
-	/* L1 PM substates require L1 */
-	if (state & PCIE_LINK_STATE_L1_1)
+	if (state & ASPM_STATE_L1_2_MASK)
+		aspm_l1ss_init(link);
+	/* L1 PM substates require L1 and should be in supported list */
+	if (state & link->aspm_support & PCIE_LINK_STATE_L1_1)
 		link->aspm_default |= ASPM_STATE_L1_1 | ASPM_STATE_L1;
-	if (state & PCIE_LINK_STATE_L1_2)
+	if (state & link->aspm_support & PCIE_LINK_STATE_L1_2)
 		link->aspm_default |= ASPM_STATE_L1_2 | ASPM_STATE_L1;
-	if (state & PCIE_LINK_STATE_L1_1_PCIPM)
+	if (state & link->aspm_support & PCIE_LINK_STATE_L1_1_PCIPM)
 		link->aspm_default |= ASPM_STATE_L1_1_PCIPM | ASPM_STATE_L1;
-	if (state & PCIE_LINK_STATE_L1_2_PCIPM)
+	if (state & link->aspm_support & PCIE_LINK_STATE_L1_2_PCIPM)
 		link->aspm_default |= ASPM_STATE_L1_2_PCIPM | ASPM_STATE_L1;
 	pcie_config_aspm_link(link, policy_to_aspm_state(link));
 
-- 
2.43.0