linux-kernel - [PATCH v3 9/9] PCI/PM: Set power.strict_midlayer in pci_pm

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Message-ID: <1925097.atdPhlSkOF@rjwysocki.net>
Date: Fri, 27 Jun 2025 21:29:16 +0200
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Linux PM <linux-pm@...r.kernel.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
 Linux ACPI <linux-acpi@...r.kernel.org>,
 Linux PCI <linux-pci@...r.kernel.org>, Ulf Hansson <ulf.hansson@...aro.org>,
 Mika Westerberg <mika.westerberg@...ux.intel.com>,
 Bjorn Helgaas <helgaas@...nel.org>
Subject: [PATCH v3 9/9] PCI/PM: Set power.strict_midlayer in pci_pm_init()

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

The PCI bus type does not expect its runtime PM suspend callback
function, pci_pm_runtime_suspend(), to be invoked at all during system-
wide suspend and resume, and it does not expect its runtime resume
callback function, pci_pm_runtime_resume(), to be invoked at any point
when runtime PM is disabled for the given device during system-wide
suspend and resume, so make it express that expectation by setting
power.strict_midlayer for all PCI devices in pci_pm_prepare() and
clear it in pci_pm_complete().

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Acked-by: Bjorn Helgaas <bhelgaas@...gle.com>
---

v2 -> v3:
   * Update subject prefix (Bjorn).
   * Update the changelog to be more precise.
   * Add Acked-by from Bjorn.

v1 -> v2:
   * Set and clear the new flag in "prepare" and "complete" to allow
     pm_runtime_force_suspend() invoked from driver remove callbacks to
     work.
   * Update subject and changelog.

---
 drivers/pci/pci-driver.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -708,6 +708,8 @@
 	struct pci_dev *pci_dev = to_pci_dev(dev);
 	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;

+	dev_pm_set_strict_midlayer(dev, true);
+
 	if (pm && pm->prepare) {
 		int error = pm->prepare(dev);
 		if (error < 0)
@@ -749,6 +751,8 @@
 		if (pci_dev->current_state < pre_sleep_state)
 			pm_request_resume(dev);
 	}
+
+	dev_pm_set_strict_midlayer(dev, false);
 }

 #else /* !CONFIG_PM_SLEEP */