linux-kernel - [PATCH v2 1/3] PCI/ASPM: Store disabled ASPM states

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Date:   Thu, 21 Oct 2021 11:51:57 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     bhelgaas@...gle.com
Cc:     hkallweit1@...il.com, anthony.wong@...onical.com,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        Kai-Heng Feng <kai.heng.feng@...onical.com>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Vidya Sagar <vidyas@...dia.com>,
        Logan Gunthorpe <logang@...tatee.com>
Subject: [PATCH v2 1/3] PCI/ASPM: Store disabled ASPM states

If we use sysfs to disable L1 ASPM, then enable one L1 ASPM substate
again, all other substates will also be enabled too:

link# grep . *
clkpm:1
l0s_aspm:1
l1_1_aspm:1
l1_1_pcipm:1
l1_2_aspm:1
l1_2_pcipm:1
l1_aspm:1

link# echo 0 > l1_aspm

link# grep . *
clkpm:1
l0s_aspm:1
l1_1_aspm:0
l1_1_pcipm:0
l1_2_aspm:0
l1_2_pcipm:0
l1_aspm:0

link# echo 1 > l1_2_aspm

link# grep . *
clkpm:1
l0s_aspm:1
l1_1_aspm:1
l1_1_pcipm:1
l1_2_aspm:1
l1_2_pcipm:1
l1_aspm:1

This is because disabled ASPM states weren't saved, so enable any of the
substate will also enable others.

So store the disabled ASPM states for consistency.

Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
---
v2:
 - Drop redundant change.

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

diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 013a47f587ce..30b1bc899026 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -658,6 +658,8 @@ static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)
 	/* Setup initial capable state. Will be updated later */
 	link->aspm_capable = link->aspm_support;
 
+	link->aspm_disable = link->aspm_capable & ~link->aspm_default;
+
 	/* Get and check endpoint acceptable latencies */
 	list_for_each_entry(child, &linkbus->devices, bus_list) {
 		u32 reg32, encoding;
@@ -1231,6 +1233,9 @@ static ssize_t aspm_attr_store_common(struct device *dev,
 		if (state & ASPM_STATE_L1SS)
 			link->aspm_disable &= ~ASPM_STATE_L1;
 	} else {
+		if (state == ASPM_STATE_L1)
+			state |= ASPM_STATE_L1SS;
+
 		link->aspm_disable |= state;
 	}
 
-- 
2.32.0