[Linux-kernel-mentees] [PATCH v3 10/12] fbdev: vt8623fb: use generic power management

[Vaibhav Gupta]

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 vt8623_pci_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 "vt8623_pci_pm_ops" const variable. This also avoids the
step of checking "state.event == PM_EVENT_FREEZE" every time the callback
is invoked.

Signed-off-by: Vaibhav Gupta <vaibhavgupta40 at gmail.com>
---
 drivers/video/fbdev/vt8623fb.c | 41 ++++++++++++++--------------------
 1 file changed, 17 insertions(+), 24 deletions(-)

diff --git a/drivers/video/fbdev/vt8623fb.c b/drivers/video/fbdev/vt8623fb.c
index 7b3eef1b893f..c488e0117758 100644
--- a/drivers/video/fbdev/vt8623fb.c
+++ b/drivers/video/fbdev/vt8623fb.c
@@ -815,12 +815,11 @@ static void vt8623_pci_remove(struct pci_dev *dev)
 }
 
 
-#ifdef CONFIG_PM
 /* PCI suspend */
 
-static int vt8623_pci_suspend(struct pci_dev* dev, pm_message_t state)
+static int __maybe_unused vt8623_pci_suspend(struct device *dev)
 {
-	struct fb_info *info = pci_get_drvdata(dev);
+	struct fb_info *info = dev_get_drvdata(dev);
 	struct vt8623fb_info *par = info->par;
 
 	dev_info(info->device, "suspend\n");
@@ -828,7 +827,7 @@ static int vt8623_pci_suspend(struct pci_dev* dev, pm_message_t state)
 	console_lock();
 	mutex_lock(&(par->open_lock));
 
-	if ((state.event == PM_EVENT_FREEZE) || (par->ref_count == 0)) {
+	if (par->ref_count == 0) {
 		mutex_unlock(&(par->open_lock));
 		console_unlock();
 		return 0;
@@ -836,10 +835,6 @@ static int vt8623_pci_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();
 
@@ -849,9 +844,9 @@ static int vt8623_pci_suspend(struct pci_dev* dev, pm_message_t state)
 
 /* PCI resume */
 
-static int vt8623_pci_resume(struct pci_dev* dev)
+static int __maybe_unused vt8623_pci_resume(struct device *dev)
 {
-	struct fb_info *info = pci_get_drvdata(dev);
+	struct fb_info *info = dev_get_drvdata(dev);
 	struct vt8623fb_info *par = info->par;
 
 	dev_info(info->device, "resume\n");
@@ -862,14 +857,6 @@ static int vt8623_pci_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;
-
-	pci_set_master(dev);
-
 	vt8623fb_set_par(info);
 	fb_set_suspend(info, 0);
 
@@ -879,10 +866,17 @@ static int vt8623_pci_resume(struct pci_dev* dev)
 
 	return 0;
 }
-#else
-#define vt8623_pci_suspend NULL
-#define vt8623_pci_resume NULL
-#endif /* CONFIG_PM */
+
+static const struct dev_pm_ops vt8623_pci_pm_ops = {
+#ifdef CONFIG_PM_SLEEP
+	.suspend	= vt8623_pci_suspend,
+	.resume		= vt8623_pci_resume,
+	.freeze		= NULL,
+	.thaw		= vt8623_pci_resume,
+	.poweroff	= vt8623_pci_suspend,
+	.restore	= vt8623_pci_resume,
+#endif /* CONFIG_PM_SLEEP */
+};
 
 /* List of boards that we are trying to support */
 
@@ -898,8 +892,7 @@ static struct pci_driver vt8623fb_pci_driver = {
 	.id_table	= vt8623_devices,
 	.probe		= vt8623_pci_probe,
 	.remove		= vt8623_pci_remove,
-	.suspend	= vt8623_pci_suspend,
-	.resume		= vt8623_pci_resume,
+	.driver.pm	= &vt8623_pci_pm_ops,
 };
 
 /* Cleanup */
-- 
2.28.0