[Linux-kernel-mentees] [PATCH v2 3/3] via-agp: use generic power management

[Vaibhav Gupta <vaibhavgupta40@gmail.com>]

Drivers should do only device-specific jobs. But in general, drivers using
legacy PCI PM framework for .suspend()/.resume() have to manage many PCI
PM-related tasks themselves which can be done by PCI Core itself. This
brings extra load on the driver and it directly calls PCI helper functions
to handle them.

Switch to the new generic framework by updating function signatures and
define a "struct dev_pm_ops" variable to bind PM callbacks. Also, remove
unnecessary calls to the PCI Helper functions along with the legacy
.suspend & .resume bindings.

After upgrading, .suspend() became an empty-body function, hence defined as
NULL.

Signed-off-by: Vaibhav Gupta <vaibhavgupta40@gmail.com>
---
 drivers/char/agp/via-agp.c | 25 +++++--------------------
 1 file changed, 5 insertions(+), 20 deletions(-)

diff --git a/drivers/char/agp/via-agp.c b/drivers/char/agp/via-agp.c
index 87a92a044570..a460ae352772 100644
--- a/drivers/char/agp/via-agp.c
+++ b/drivers/char/agp/via-agp.c
@@ -492,22 +492,11 @@ static void agp_via_remove(struct pci_dev *pdev)
 	agp_put_bridge(bridge);
 }
 
-#ifdef CONFIG_PM
+#define agp_via_suspend NULL
 
-static int agp_via_suspend(struct pci_dev *pdev, pm_message_t state)
+static int __maybe_unused agp_via_resume(struct device *dev)
 {
-	pci_save_state (pdev);
-	pci_set_power_state (pdev, PCI_D3hot);
-
-	return 0;
-}
-
-static int agp_via_resume(struct pci_dev *pdev)
-{
-	struct agp_bridge_data *bridge = pci_get_drvdata(pdev);
-
-	pci_set_power_state (pdev, PCI_D0);
-	pci_restore_state(pdev);
+	struct agp_bridge_data *bridge = dev_get_drvdata(dev);
 
 	if (bridge->driver == &via_agp3_driver)
 		return via_configure_agp3();
@@ -517,8 +506,6 @@ static int agp_via_resume(struct pci_dev *pdev)
 	return 0;
 }
 
-#endif /* CONFIG_PM */
-
 /* must be the same order as name table above */
 static const struct pci_device_id agp_via_pci_table[] = {
 #define ID(x) \
@@ -567,16 +554,14 @@ static const struct pci_device_id agp_via_pci_table[] = {
 
 MODULE_DEVICE_TABLE(pci, agp_via_pci_table);
 
+static SIMPLE_DEV_PM_OPS(agp_via_pm_ops, agp_via_suspend, agp_via_resume);
 
 static struct pci_driver agp_via_pci_driver = {
 	.name		= "agpgart-via",
 	.id_table	= agp_via_pci_table,
 	.probe		= agp_via_probe,
 	.remove		= agp_via_remove,
-#ifdef CONFIG_PM
-	.suspend	= agp_via_suspend,
-	.resume		= agp_via_resume,
-#endif
+	.driver.pm      = &agp_via_pm_ops,
 };
 
 
-- 
2.30.0

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