linux-kernel - [PATCH v2 9/9] PCI/PM: Replace pci_set_power_state() in pci_pm_thaw

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Date:   Mon, 11 Apr 2022 16:33:02 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Linux PCI <linux-pci@...r.kernel.org>
Cc:     Linux PM <linux-pm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Bjorn Helgaas <helgaas@...nel.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>
Subject: [PATCH v2 9/9] PCI/PM: Replace pci_set_power_state() in pci_pm_thaw_noirq()

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

Calling pci_set_power_state() to put the given device into D0 in
pci_pm_thaw_noirq() may cause it to restore the device's BARs, which
is redundant before calling pci_restore_state(), so replace it with
a direct pci_power_up() call followed by pci_update_current_state()
if it returns a nonzeor value, in analogy with
pci_pm_default_resume_early().

Avoid code duplication by introducing a wrapper function to contain
the repeating pattern and calling it in both places.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---

New patch in v2.

---
 drivers/pci/pci-driver.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

Index: linux-pm/drivers/pci/pci-driver.c
===================================================================
--- linux-pm.orig/drivers/pci/pci-driver.c
+++ linux-pm/drivers/pci/pci-driver.c
@@ -551,11 +551,15 @@ static void pci_pm_default_resume(struct
 	pci_enable_wake(pci_dev, PCI_D0, false);
 }
 
-static void pci_pm_default_resume_early(struct pci_dev *pci_dev)
+static void pci_pm_power_up_and_verify_state(struct pci_dev *pci_dev)
 {
 	if (pci_power_up(pci_dev))
 		pci_update_current_state(pci_dev, PCI_D0);
+}
 
+static void pci_pm_default_resume_early(struct pci_dev *pci_dev)
+{
+	pci_pm_power_up_and_verify_state(pci_dev);
 	pci_restore_state(pci_dev);
 	pci_pme_restore(pci_dev);
 }
@@ -1080,7 +1084,7 @@ static int pci_pm_thaw_noirq(struct devi
 	 * in case the driver's "freeze" callbacks put it into a low-power
 	 * state.
 	 */
-	pci_set_power_state(pci_dev, PCI_D0);
+	pci_pm_power_up_and_verify_state(pci_dev);
 	pci_restore_state(pci_dev);
 
 	if (pci_has_legacy_pm_support(pci_dev))