linux-kernel - [PATCH] PCI/ASPM: Clarify that pcie_aspm=off means leave ASPM untouched

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Date: Mon, 29 Apr 2024 14:18:21 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: linux-pci@...r.kernel.org
Cc: Vidya Sagar <vidyas@...dia.com>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
	"Maciej W . Rozycki" <macro@...am.me.uk>,
	"David E . Box" <david.e.box@...ux.intel.com>,
	Johan Hovold <johan+linaro@...nel.org>,
	Heiner Kallweit <hkallweit1@...il.com>,
	Ajay Agarwal <ajayagarwal@...gle.com>,
	linux-kernel@...r.kernel.org,
	Bjorn Helgaas <bhelgaas@...gle.com>
Subject: [PATCH] PCI/ASPM: Clarify that pcie_aspm=off means leave ASPM untouched

From: Bjorn Helgaas <bhelgaas@...gle.com>

Previously we claimed "pcie_aspm=off" meant that ASPM would be disabled,
which is wrong.

Correct this to say that with "pcie_aspm=off", Linux doesn't touch any ASPM
configuration at all.  ASPM may have been enabled by firmware, and that
will be left unchanged.  See "aspm_support_enabled".

Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
---
 Documentation/admin-guide/kernel-parameters.txt | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index bb884c14b2f6..4bc281d6e8d3 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4590,9 +4590,10 @@
 		norid		[S390] ignore the RID field and force use of
 				one PCI domain per PCI function
 
-	pcie_aspm=	[PCIE] Forcibly enable or disable PCIe Active State Power
+	pcie_aspm=	[PCIE] Forcibly enable or ignore PCIe Active State Power
 			Management.
-		off	Disable ASPM.
+		off	Don't touch ASPM configuration at all.  Leave any
+			configuration done by firmware unchanged.
 		force	Enable ASPM even on devices that claim not to support it.
 			WARNING: Forcing ASPM on may cause system lockups.
 
-- 
2.34.1