[Linux-kernel-mentees] [PATCH v1] [media] bttv: use generic power management

[Vaibhav Gupta]

Drivers using legacy power management .suspen()/.resume() callbacks
have to manage PCI states and device's PM states themselves. They also
need to take care of standard configuration registers.

Switch to generic power management framework using a single
"struct dev_pm_ops" variable to take the unnecessary load from the driver.
This also avoids the need for the driver to directly call most of the PCI
helper functions and device power state control functions, as through
the generic framework PCI Core takes care of the necessary operations,
and drivers are required to do only device-specific jobs.

Signed-off-by: Vaibhav Gupta <vaibhavgupta40 at gmail.com>
---
 drivers/media/pci/bt8xx/bttv-driver.c | 56 ++++++++-------------------
 1 file changed, 16 insertions(+), 40 deletions(-)

diff --git a/drivers/media/pci/bt8xx/bttv-driver.c b/drivers/media/pci/bt8xx/bttv-driver.c
index 9144f795fb93..cb8d955d1d5d 100644
--- a/drivers/media/pci/bt8xx/bttv-driver.c
+++ b/drivers/media/pci/bt8xx/bttv-driver.c
@@ -4263,15 +4263,14 @@ static void bttv_remove(struct pci_dev *pci_dev)
 	return;
 }
 
-#ifdef CONFIG_PM
-static int bttv_suspend(struct pci_dev *pci_dev, pm_message_t state)
+static int __maybe_unused bttv_suspend(struct device *dev)
 {
-	struct v4l2_device *v4l2_dev = pci_get_drvdata(pci_dev);
+	struct v4l2_device *v4l2_dev = dev_get_drvdata(dev);
 	struct bttv *btv = to_bttv(v4l2_dev);
 	struct bttv_buffer_set idle;
 	unsigned long flags;
 
-	dprintk("%d: suspend %d\n", btv->c.nr, state.event);
+	dprintk("%d: suspend\n", btv->c.nr);
 
 	/* stop dma + irqs */
 	spin_lock_irqsave(&btv->s_lock,flags);
@@ -4291,42 +4290,19 @@ static int bttv_suspend(struct pci_dev *pci_dev, pm_message_t state)
 	btv->state.gpio_enable = btread(BT848_GPIO_OUT_EN);
 	btv->state.gpio_data   = gpio_read();
 
-	/* save pci state */
-	pci_save_state(pci_dev);
-	if (0 != pci_set_power_state(pci_dev, pci_choose_state(pci_dev, state))) {
-		pci_disable_device(pci_dev);
-		btv->state.disabled = 1;
-	}
+	btv->state.disabled = 1;
 	return 0;
 }
 
-static int bttv_resume(struct pci_dev *pci_dev)
+static int __maybe_unused bttv_resume(struct device *dev)
 {
-	struct v4l2_device *v4l2_dev = pci_get_drvdata(pci_dev);
+	struct v4l2_device *v4l2_dev = dev_get_drvdata(dev);
 	struct bttv *btv = to_bttv(v4l2_dev);
 	unsigned long flags;
-	int err;
 
 	dprintk("%d: resume\n", btv->c.nr);
 
-	/* restore pci state */
-	if (btv->state.disabled) {
-		err=pci_enable_device(pci_dev);
-		if (err) {
-			pr_warn("%d: Can't enable device\n", btv->c.nr);
-			return err;
-		}
-		btv->state.disabled = 0;
-	}
-	err=pci_set_power_state(pci_dev, PCI_D0);
-	if (err) {
-		pci_disable_device(pci_dev);
-		pr_warn("%d: Can't enable device\n", btv->c.nr);
-		btv->state.disabled = 1;
-		return err;
-	}
-
-	pci_restore_state(pci_dev);
+	btv->state.disabled = 0;
 
 	/* restore bt878 state */
 	bttv_reinit_bt848(btv);
@@ -4344,7 +4320,6 @@ static int bttv_resume(struct pci_dev *pci_dev)
 	spin_unlock_irqrestore(&btv->s_lock,flags);
 	return 0;
 }
-#endif
 
 static const struct pci_device_id bttv_pci_tbl[] = {
 	{PCI_VDEVICE(BROOKTREE, PCI_DEVICE_ID_BT848), 0},
@@ -4357,15 +4332,16 @@ static const struct pci_device_id bttv_pci_tbl[] = {
 
 MODULE_DEVICE_TABLE(pci, bttv_pci_tbl);
 
+static SIMPLE_DEV_PM_OPS(bttv_pm_ops,
+			 bttv_suspend,
+			 bttv_resume);
+
 static struct pci_driver bttv_pci_driver = {
-	.name     = "bttv",
-	.id_table = bttv_pci_tbl,
-	.probe    = bttv_probe,
-	.remove   = bttv_remove,
-#ifdef CONFIG_PM
-	.suspend  = bttv_suspend,
-	.resume   = bttv_resume,
-#endif
+	.name      = "bttv",
+	.id_table  = bttv_pci_tbl,
+	.probe     = bttv_probe,
+	.remove    = bttv_remove,
+	.driver.pm = &bttv_pm_ops,
 };
 
 static int __init bttv_init_module(void)
-- 
2.27.0