[Linux-kernel-mentees] [PATCH v3 09/12] fbdev: i740fb: 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.

The i740fb_suspend() is not designed to function in the case of Freeze.
Thus, the code checked for "if (state.event == PM_EVENT_FREEZE....)". This
is because, in the legacy framework, this callback was invoked even in the
event of Freeze. Hence, added the load of unnecessary function-call.

The goal can be achieved by binding the callback with only ".suspend" and
".poweroff" in the "i740fb_pm_ops" const variable. This also avoids the
step of checking "if (state.event == PM_EVENT_FREEZE....)" every time the
callback is invoked.

Signed-off-by: Vaibhav Gupta <vaibhavgupta40@gmail.com>
---
 drivers/video/fbdev/i740fb.c | 40 +++++++++++++++---------------------
 1 file changed, 16 insertions(+), 24 deletions(-)

diff --git a/drivers/video/fbdev/i740fb.c b/drivers/video/fbdev/i740fb.c
index c65ec7386e87..8d7f06fc8a5a 100644
--- a/drivers/video/fbdev/i740fb.c
+++ b/drivers/video/fbdev/i740fb.c
@@ -1175,16 +1175,11 @@ static void i740fb_remove(struct pci_dev *dev)
 	}
 }
 
-#ifdef CONFIG_PM
-static int i740fb_suspend(struct pci_dev *dev, pm_message_t state)
+static int __maybe_unused i740fb_suspend(struct device *dev)
 {
-	struct fb_info *info = pci_get_drvdata(dev);
+	struct fb_info *info = dev_get_drvdata(dev);
 	struct i740fb_par *par = info->par;
 
-	/* don't disable console during hibernation and wakeup from it */
-	if (state.event == PM_EVENT_FREEZE || state.event == PM_EVENT_PRETHAW)
-		return 0;
-
 	console_lock();
 	mutex_lock(&(par->open_lock));
 
@@ -1197,19 +1192,15 @@ static int i740fb_suspend(struct pci_dev *dev, pm_message_t state)
 
 	fb_set_suspend(info, 1);
 
-	pci_save_state(dev);
-	pci_disable_device(dev);
-	pci_set_power_state(dev, pci_choose_state(dev, state));
-
 	mutex_unlock(&(par->open_lock));
 	console_unlock();
 
 	return 0;
 }
 
-static int i740fb_resume(struct pci_dev *dev)
+static int __maybe_unused i740fb_resume(struct device *dev)
 {
-	struct fb_info *info = pci_get_drvdata(dev);
+	struct fb_info *info = dev_get_drvdata(dev);
 	struct i740fb_par *par = info->par;
 
 	console_lock();
@@ -1218,11 +1209,6 @@ static int i740fb_resume(struct pci_dev *dev)
 	if (par->ref_count == 0)
 		goto fail;
 
-	pci_set_power_state(dev, PCI_D0);
-	pci_restore_state(dev);
-	if (pci_enable_device(dev))
-		goto fail;
-
 	i740fb_set_par(info);
 	fb_set_suspend(info, 0);
 
@@ -1231,10 +1217,17 @@ static int i740fb_resume(struct pci_dev *dev)
 	console_unlock();
 	return 0;
 }
-#else
-#define i740fb_suspend NULL
-#define i740fb_resume NULL
-#endif /* CONFIG_PM */
+
+static const struct dev_pm_ops i740fb_pm_ops = {
+#ifdef CONFIG_PM_SLEEP
+	.suspend	= i740fb_suspend,
+	.resume		= i740fb_resume,
+	.freeze		= NULL,
+	.thaw		= i740fb_resume,
+	.poweroff	= i740fb_suspend,
+	.restore	= i740fb_resume,
+#endif /* CONFIG_PM_SLEEP */
+};
 
 #define I740_ID_PCI 0x00d1
 #define I740_ID_AGP 0x7800
@@ -1251,8 +1244,7 @@ static struct pci_driver i740fb_driver = {
 	.id_table	= i740fb_id_table,
 	.probe		= i740fb_probe,
 	.remove		= i740fb_remove,
-	.suspend	= i740fb_suspend,
-	.resume		= i740fb_resume,
+	.driver.pm	= &i740fb_pm_ops,
 };
 
 #ifndef MODULE
-- 
2.28.0

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