[Linux-kernel-mentees] [PATCH v2 03/12] fbdev: via-core: use generic power management

Vaibhav Gupta vaibhavgupta40 at gmail.com
Mon Aug 10 18:57:14 UTC 2020


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. Additionally, this helps us to remove the
unnecessary call to via_suspend() in the event of Freeze and Hibernate, as
the function does nothing in their case.

Signed-off-by: Vaibhav Gupta <vaibhavgupta40 at gmail.com>
---
 drivers/video/fbdev/via/via-core.c | 39 ++++++++++++------------------
 include/linux/via-core.h           |  2 --
 2 files changed, 16 insertions(+), 25 deletions(-)

diff --git a/drivers/video/fbdev/via/via-core.c b/drivers/video/fbdev/via/via-core.c
index 703ddee9a244..89d75079b730 100644
--- a/drivers/video/fbdev/via/via-core.c
+++ b/drivers/video/fbdev/via/via-core.c
@@ -558,9 +558,8 @@ static void via_teardown_subdevs(void)
 /*
  * Power management functions
  */
-#ifdef CONFIG_PM
-static LIST_HEAD(viafb_pm_hooks);
-static DEFINE_MUTEX(viafb_pm_hooks_lock);
+static __maybe_unused LIST_HEAD(viafb_pm_hooks);
+static __maybe_unused DEFINE_MUTEX(viafb_pm_hooks_lock);
 
 void viafb_pm_register(struct viafb_pm_hooks *hooks)
 {
@@ -580,12 +579,10 @@ void viafb_pm_unregister(struct viafb_pm_hooks *hooks)
 }
 EXPORT_SYMBOL_GPL(viafb_pm_unregister);
 
-static int via_suspend(struct pci_dev *pdev, pm_message_t state)
+static int __maybe_unused via_suspend(struct device *dev)
 {
 	struct viafb_pm_hooks *hooks;
 
-	if (state.event != PM_EVENT_SUSPEND)
-		return 0;
 	/*
 	 * "I've occasionally hit a few drivers that caused suspend
 	 * failures, and each and every time it was a driver bug, and
@@ -600,24 +597,13 @@ static int via_suspend(struct pci_dev *pdev, pm_message_t state)
 		hooks->suspend(hooks->private);
 	mutex_unlock(&viafb_pm_hooks_lock);
 
-	pci_save_state(pdev);
-	pci_disable_device(pdev);
-	pci_set_power_state(pdev, pci_choose_state(pdev, state));
 	return 0;
 }
 
-static int via_resume(struct pci_dev *pdev)
+static int __maybe_unused via_resume(struct device *dev)
 {
 	struct viafb_pm_hooks *hooks;
 
-	/* Get the bus side powered up */
-	pci_set_power_state(pdev, PCI_D0);
-	pci_restore_state(pdev);
-	if (pci_enable_device(pdev))
-		return 0;
-
-	pci_set_master(pdev);
-
 	/* Now bring back any subdevs */
 	mutex_lock(&viafb_pm_hooks_lock);
 	list_for_each_entry(hooks, &viafb_pm_hooks, list)
@@ -626,7 +612,6 @@ static int via_resume(struct pci_dev *pdev)
 
 	return 0;
 }
-#endif /* CONFIG_PM */
 
 static int via_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 {
@@ -712,15 +697,23 @@ static const struct pci_device_id via_pci_table[] = {
 };
 MODULE_DEVICE_TABLE(pci, via_pci_table);
 
+static const struct dev_pm_ops via_pm_ops = {
+#ifdef CONFIG_PM_SLEEP
+	.suspend	= via_suspend,
+	.resume		= via_resume,
+	.freeze		= NULL,
+	.thaw		= via_resume,
+	.poweroff	= NULL,
+	.restore	= via_resume,
+#endif
+};
+
 static struct pci_driver via_driver = {
 	.name		= "viafb",
 	.id_table	= via_pci_table,
 	.probe		= via_pci_probe,
 	.remove		= via_pci_remove,
-#ifdef CONFIG_PM
-	.suspend	= via_suspend,
-	.resume		= via_resume,
-#endif
+	.driver.pm	= &via_pm_ops,
 };
 
 static int __init via_core_init(void)
diff --git a/include/linux/via-core.h b/include/linux/via-core.h
index 9e802deedb2d..8737599b9148 100644
--- a/include/linux/via-core.h
+++ b/include/linux/via-core.h
@@ -47,7 +47,6 @@ struct via_port_cfg {
 /*
  * Allow subdevs to register suspend/resume hooks.
  */
-#ifdef CONFIG_PM
 struct viafb_pm_hooks {
 	struct list_head list;
 	int (*suspend)(void *private);
@@ -57,7 +56,6 @@ struct viafb_pm_hooks {
 
 void viafb_pm_register(struct viafb_pm_hooks *hooks);
 void viafb_pm_unregister(struct viafb_pm_hooks *hooks);
-#endif /* CONFIG_PM */
 
 /*
  * This is the global viafb "device" containing stuff needed by
-- 
2.27.0



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