linux-kernel - [PATCH 4/5] agp/ati: Convert to generic power management

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Date:   Mon,  6 Jun 2022 22:43:39 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     David Airlie <airlied@...ux.ie>,
        "Rafael J . Wysocki" <rafael@...nel.org>
Cc:     Vaibhav Gupta <vaibhavgupta40@...il.com>, linux-pm@...r.org,
        linux-pci@...r.org, linux-kernel@...r.kernel.org,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: [PATCH 4/5] agp/ati: Convert to generic power management

From: Bjorn Helgaas <bhelgaas@...gle.com>

Convert agpgart-ati from legacy PCI power management to the generic power
management framework.

Previously agpgart-ati used legacy PCI power management, and
agp_ati_suspend() and agp_ati_resume() were responsible for both
device-specific things and generic PCI things like saving and restoring
config space and managing power state:

  agp_ati_suspend
    pci_save_state                         <-- generic PCI
    pci_set_power_state(PCI_D3hot)         <-- generic PCI

  agp_ati_resume
    pci_set_power_state(PCI_D0)            <-- generic PCI
    pci_restore_state                      <-- generic PCI
    ati_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_ati_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_ati_resume                     # driver->pm->resume
          ati_configure                    <-- device-specific

Based on 0aeddbd0cb07 ("via-agp: convert to generic power management") by
Vaibhav Gupta <vaibhavgupta40@...il.com>.

Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
---
 drivers/char/agp/ati-agp.c | 22 ++++------------------
 1 file changed, 4 insertions(+), 18 deletions(-)

diff --git a/drivers/char/agp/ati-agp.c b/drivers/char/agp/ati-agp.c
index 6f5530482d83..fc8897c2ed4d 100644
--- a/drivers/char/agp/ati-agp.c
+++ b/drivers/char/agp/ati-agp.c
@@ -238,23 +238,10 @@ static int ati_configure(void)
 }
 
 
-#ifdef CONFIG_PM
-static int agp_ati_suspend(struct pci_dev *dev, pm_message_t state)
+static int __maybe_unused agp_ati_resume(struct device *dev)
 {
-	pci_save_state(dev);
-	pci_set_power_state(dev, PCI_D3hot);
-
-	return 0;
-}
-
-static int agp_ati_resume(struct pci_dev *dev)
-{
-	pci_set_power_state(dev, PCI_D0);
-	pci_restore_state(dev);
-
 	return ati_configure();
 }
-#endif
 
 /*
  *Since we don't need contiguous memory we just try
@@ -559,15 +546,14 @@ static const struct pci_device_id agp_ati_pci_table[] = {
 
 MODULE_DEVICE_TABLE(pci, agp_ati_pci_table);
 
+static SIMPLE_DEV_PM_OPS(agp_ati_pm_ops, NULL, agp_ati_resume);
+
 static struct pci_driver agp_ati_pci_driver = {
 	.name		= "agpgart-ati",
 	.id_table	= agp_ati_pci_table,
 	.probe		= agp_ati_probe,
 	.remove		= agp_ati_remove,
-#ifdef CONFIG_PM
-	.suspend	= agp_ati_suspend,
-	.resume		= agp_ati_resume,
-#endif
+	.driver.pm	= &agp_ati_pm_ops,
 };
 
 static int __init agp_ati_init(void)
-- 
2.25.1