linux-kernel - [PATCH v3 2/3] sis-agp: convert to generic power management

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Date:   Wed,  8 Dec 2021 13:33:04 -0600
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     David Airlie <airlied@...ux.ie>
Cc:     Vaibhav Gupta <vaibhav.varodek@...il.com>,
        Vaibhav Gupta <vaibhavgupta40@...il.com>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        Shuah Khan <skhan@...uxfoundation.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: [PATCH v3 2/3] sis-agp: convert to generic power management

From: Vaibhav Gupta <vaibhavgupta40@...il.com>

Convert sis-agp from legacy PCI power management to the generic power
management framework.

Previously, sis-agp used legacy PCI power management, and agp_sis_suspend()
and agp_sis_resume() were responsible for both device-specific things and
generic PCI things:

  agp_sis_suspend
    pci_save_state(pdev)                <-- generic PCI
    pci_set_power_state(pdev, pci_choose_state(pdev, state)) <-- generic PCI

  agp_sis_resume
    pci_set_power_state(pdev, PCI_D0)   <-- generic PCI
    pci_restore_state(pdev)             <-- generic PCI
    sis_driver.configure()              <-- device-specific

With generic power management, the PCI bus PM methods do the generic PCI
things, and the driver needs only the device-specific part, i.e.,

  suspend_devices_and_enter
    dpm_suspend_start(PMSG_SUSPEND)
      pci_pm_suspend                    # PCI bus .suspend() method
        agp_sis_suspend                 <-- not needed at all; removed
    suspend_enter
      dpm_suspend_noirq(PMSG_SUSPEND)
        pci_pm_suspend_noirq            # PCI bus .suspend_noirq() method
          pci_save_state                <-- generic PCI
          pci_prepare_to_sleep          <-- generic PCI
            pci_set_power_state
    ...
    dpm_resume_end(PMSG_RESUME)
      pci_pm_resume                     # PCI bus .resume() method
        pci_restore_standard_config
          pci_set_power_state(PCI_D0)   <-- generic PCI
          pci_restore_state             <-- generic PCI
        agp_sis_resume                  # dev->driver->pm->resume
          sis_driver.configure()        <-- device-specific

[bhelgaas: commit log]
Signed-off-by: Vaibhav Gupta <vaibhavgupta40@...il.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
---
 drivers/char/agp/sis-agp.c | 25 ++++++-------------------
 1 file changed, 6 insertions(+), 19 deletions(-)

diff --git a/drivers/char/agp/sis-agp.c b/drivers/char/agp/sis-agp.c
index 14909fc5d767..f8a02f4bef1b 100644
--- a/drivers/char/agp/sis-agp.c
+++ b/drivers/char/agp/sis-agp.c
@@ -217,26 +217,14 @@ static void agp_sis_remove(struct pci_dev *pdev)
 	agp_put_bridge(bridge);
 }
 
-#ifdef CONFIG_PM
+#define agp_sis_suspend NULL
 
-static int agp_sis_suspend(struct pci_dev *pdev, pm_message_t state)
+static int __maybe_unused agp_sis_resume(
+	__attribute__((unused)) struct device *dev)
 {
-	pci_save_state(pdev);
-	pci_set_power_state(pdev, pci_choose_state(pdev, state));
-
-	return 0;
-}
-
-static int agp_sis_resume(struct pci_dev *pdev)
-{
-	pci_set_power_state(pdev, PCI_D0);
-	pci_restore_state(pdev);
-
 	return sis_driver.configure();
 }
 
-#endif /* CONFIG_PM */
-
 static const struct pci_device_id agp_sis_pci_table[] = {
 	{
 		.class		= (PCI_CLASS_BRIDGE_HOST << 8),
@@ -419,15 +407,14 @@ static const struct pci_device_id agp_sis_pci_table[] = {
 
 MODULE_DEVICE_TABLE(pci, agp_sis_pci_table);
 
+static SIMPLE_DEV_PM_OPS(agp_sis_pm_ops, agp_sis_suspend, agp_sis_resume);
+
 static struct pci_driver agp_sis_pci_driver = {
 	.name		= "agpgart-sis",
 	.id_table	= agp_sis_pci_table,
 	.probe		= agp_sis_probe,
 	.remove		= agp_sis_remove,
-#ifdef CONFIG_PM
-	.suspend	= agp_sis_suspend,
-	.resume		= agp_sis_resume,
-#endif
+	.driver.pm      = &agp_sis_pm_ops,
 };
 
 static int __init agp_sis_init(void)
-- 
2.25.1