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From: Jian-Hong Pan <jhp@endlessos.org>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: Johan Hovold <johan@kernel.org>,
	David Box <david.e.box@linux.intel.com>,
	=?UTF-8?q?Ilpo=20J=C3=A4rvinen?= <ilpo.jarvinen@linux.intel.com>,
	Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>,
	Mika Westerberg <mika.westerberg@linux.intel.com>,
	Damien Le Moal <dlemoal@kernel.org>,
	Nirmal Patel <nirmal.patel@linux.intel.com>,
	Jonathan Derrick <jonathan.derrick@linux.dev>,
	linux-pci@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Jian-Hong Pan <jhp@endlessos.org>
Subject: [PATCH 0/4] PCI: vmd: Enable PCI PM's L1 substates of remapped PCIe Root Port and NVMe
Date: Wed, 24 Apr 2024 18:43:13 +0800
Message-ID: <20240424104313.21011-1-jhp@endlessos.org>
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Notice the VMD remapped PCIe Root Port and NVMe have PCI PM L1 substates
capability, but they are disabled originally.

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

10000:e0:06.0 PCI bridge: Intel Corporation 11th Gen Core Processor PCIe Controller (rev 01) (prog-if 00 [Normal decode])
    ...
    Capabilities: [200 v1] L1 PM Substates
        L1SubCap: PCI-PM_L1.2+ PCI-PM_L1.1+ ASPM_L1.2+ ASPM_L1.1+ L1_PM_Substates+
        	  PortCommonModeRestoreTime=45us PortTPowerOnTime=50us
        L1SubCtl1: PCI-PM_L1.2- PCI-PM_L1.1- ASPM_L1.2+ ASPM_L1.1-
        	   T_CommonMode=45us LTR1.2_Threshold=101376ns
        L1SubCtl2: T_PwrOn=50us

10000:e1:00.0 Non-Volatile memory controller: Sandisk Corp WD Blue SN550 NVMe SSD (rev 01) (prog-if 02 [NVM Express])
    ...
    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

According to "PCIe r6.0, sec 5.5.4", to config the link between the PCIe
Root Port and the child device correctly:
* Ensure both devices are in D0 before enabling PCI-PM L1 PM Substates.
* Ensure L1.2 parameters: Common_Mode_Restore_Times, T_POWER_ON and
  LTR_L1.2_THRESHOLD are programmed properly on both devices before enable
  bits for L1.2.

Prepare this series to fix that.

Jian-Hong Pan (4):
  PCI: vmd: Set PCI devices to D0 before enable PCI PM's L1 substates
  PCI/ASPM: Add notes about enabling PCI-PM L1SS to pci_enable_link_state(_locked)
  PCI/ASPM: Introduce aspm_get_l1ss_cap()
  PCI/ASPM: Fix L1.2 parameters when enable link state

 drivers/pci/controller/vmd.c | 13 ++++++++----
 drivers/pci/pcie/aspm.c      | 41 ++++++++++++++++++++++++++++--------
 2 files changed, 41 insertions(+), 13 deletions(-)

-- 
2.44.0