diff mbox series

[SRU,N,v3,2/2] PCI/ASPM: Add notes about enabling PCI-PM L1SS to pci_enable_link_state(_locked)

Message ID 20241120061704.636295-3-en-wei.wu@canonical.com
State New
Headers show
Series System hang when running memory/memory_stress_ng test | expand

Commit Message

En-Wei Wu Nov. 20, 2024, 6:17 a.m. UTC 
From: Jian-Hong Pan <jhp@endlessos.org>

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

According to "PCIe r6.0, sec 5.5.4", add note about D0 requirement in
pci_enable_link_state() kernel-doc.

Link: https://lore.kernel.org/r/20241001083438.10070-6-jhp@endlessos.org
Signed-off-by: Jian-Hong Pan <jhp@endlessos.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
(cherry picked from commit e1714f3b1f4d2af5df26e4a0e4a70ef64b15e3ee linux-next)
Signed-off-by: En-Wei Wu <en-wei.wu@canonical.com>
---
 drivers/pci/pcie/aspm.c | 6 ++++++
 1 file changed, 6 insertions(+)
diff mbox series

Patch

diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 138ff0efa6dd..182226ce5c4e 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -1450,6 +1450,9 @@  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
  */
@@ -1466,6 +1469,9 @@  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
  *