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Message-ID: <20240930084840.13424-2-jhp@endlessos.org>
Date: Mon, 30 Sep 2024 16:48:41 +0800
From: Jian-Hong Pan <jhp@...lessos.org>
To: Bjorn Helgaas <helgaas@...nel.org>
Cc: Johan Hovold <johan@...nel.org>,
David Box <david.e.box@...ux.intel.com>,
Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...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>,
Bjorn Helgaas <bhelgaas@...gle.com>
Subject: [PATCH v11 2/3] PCI/ASPM: Add notes about enabling PCI-PM L1SS to pci_enable_link_state(_locked)
According to "PCIe r6.0, sec 5.5.4", add note about D0 requirement in
pci_enable_link_state() kernel-doc.
Signed-off-by: Jian-Hong Pan <jhp@...lessos.org>
Acked-by: Bjorn Helgaas <bhelgaas@...gle.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
---
v3:
- Fix as readable comments
v4:
- The same
v5:
- Tweak and simplify the commit message
v6~11:
- The same
drivers/pci/pcie/aspm.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index cee2365e54b8..bd0a8a05647e 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -1442,6 +1442,9 @@ static int __pci_enable_link_state(struct pci_dev *pdev, int state, bool locked)
* touch the LNKCTL register. Also note that this does not enable states
* disabled by pci_disable_link_state(). Return 0 or a negative errno.
*
+ * Note: Ensure devices are in D0 before enabling PCI-PM L1 PM Substates, per
+ * PCIe r6.0, sec 5.5.4.
+ *
* @pdev: PCI device
* @state: Mask of ASPM link states to enable
*/
@@ -1458,6 +1461,9 @@ EXPORT_SYMBOL(pci_enable_link_state);
* can't touch the LNKCTL register. Also note that this does not enable states
* disabled by pci_disable_link_state(). Return 0 or a negative errno.
*
+ * Note: Ensure devices are in D0 before enabling PCI-PM L1 PM Substates, per
+ * PCIe r6.0, sec 5.5.4.
+ *
* @pdev: PCI device
* @state: Mask of ASPM link states to enable
*
--
2.46.2
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