linux-kernel - [PATCH] PCI/PM: Put devices to low power state on shutdown

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Message-ID: <20240712062411.35732-1-kai.heng.feng@canonical.com>
Date: Fri, 12 Jul 2024 14:24:11 +0800
From: Kai-Heng Feng <kai.heng.feng@...onical.com>
To: bhelgaas@...gle.com
Cc: mario.limonciello@....com,
	mika.westerberg@...ux.intel.com,
	linux-pci@...r.kernel.org,
	linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Kai-Heng Feng <kai.heng.feng@...onical.com>
Subject: [PATCH] PCI/PM: Put devices to low power state on shutdown

Some laptops wake up after poweroff when HP Thunderbolt Dock G4 is
connected.

The following error message can be found during shutdown:
pcieport 0000:00:1d.0: AER: Correctable error message received from 0000:09:04.0
pcieport 0000:09:04.0: PCIe Bus Error: severity=Correctable, type=Data Link Layer, (Receiver ID)
pcieport 0000:09:04.0:   device [8086:0b26] error status/mask=00000080/00002000
pcieport 0000:09:04.0:    [ 7] BadDLLP

Calling aer_remove() during shutdown can quiesce the error message,
however the spurious wakeup still happens.

The issue won't happen if the device is in D3 before system shutdown, so
putting device to low power state before shutdown to solve the issue.

I don't have a sniffer so this is purely guesswork, however I believe
putting device to low power state it's the right thing to do.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=219036
Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
---
 drivers/pci/pci-driver.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index af2996d0d17f..4c6f66f3eb54 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -510,6 +510,14 @@ static void pci_device_shutdown(struct device *dev)
 	if (drv && drv->shutdown)
 		drv->shutdown(pci_dev);
 
+	/*
+	 * If driver already changed device's power state, it can mean the
+	 * wakeup setting is in place, or a workaround is used. Hence keep it
+	 * as is.
+	 */
+	if (!kexec_in_progress && pci_dev->current_state == PCI_D0)
+		pci_prepare_to_sleep(pci_dev);
+
 	/*
 	 * If this is a kexec reboot, turn off Bus Master bit on the
 	 * device to tell it to not continue to do DMA. Don't touch
-- 
2.43.0