[PATCH 1/1] dw9768: Enable low-power probe on ACPI

[Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>]

Add support for low-power probe to the driver. Also fix runtime PM API
usage in the driver.

Much of the hassle comes from different factors affecting device power
states during probe for ACPI and DT.

Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
Fixes: 859891228e56 ("media: i2c: dw9768: Add DW9768 VCM driver")
---
Hi folks,

I think I don't have the hardware so this is untested (apart from
compiling). Testing would be appreciated.

Much of the ugliness comes from having to test between DT and ACPI as DT
has no means to tell the device should not be powered on during probe. To
be added once someone needs it I guess.

 drivers/media/i2c/dw9768.c | 33 +++++++++++++++++++++++++--------
 1 file changed, 25 insertions(+), 8 deletions(-)

diff --git a/drivers/media/i2c/dw9768.c b/drivers/media/i2c/dw9768.c
index c086580efac78..60ae0adf51744 100644
--- a/drivers/media/i2c/dw9768.c
+++ b/drivers/media/i2c/dw9768.c
@@ -414,6 +414,7 @@ static int dw9768_probe(struct i2c_client *client)
 {
 	struct device *dev = &client->dev;
 	struct dw9768 *dw9768;
+	bool full_power;
 	unsigned int i;
 	int ret;
 
@@ -469,13 +470,23 @@ static int dw9768_probe(struct i2c_client *client)
 
 	dw9768->sd.entity.function = MEDIA_ENT_F_LENS;
 
+	/*
+	 * Figure out whether we're going to power up the device here. Generally
+	 * this is done if CONFIG_PM is disabled in a DT system or the device is
+	 * to be powered on in an ACPI system. Similarly for power off in
+	 * remove.
+	 */
 	pm_runtime_enable(dev);
-	if (!pm_runtime_enabled(dev)) {
+	full_power = (is_acpi_node(dev_fwnode(dev)) &&
+		      acpi_dev_state_d0(dev)) ||
+		     (is_of_node(dev_fwnode(dev)) && !pm_runtime_enabled(dev));
+	if (full_power) {
 		ret = dw9768_runtime_resume(dev);
 		if (ret < 0) {
 			dev_err(dev, "failed to power on: %d\n", ret);
 			goto err_clean_entity;
 		}
+		pm_runtime_set_active(dev);
 	}
 
 	ret = v4l2_async_register_subdev(&dw9768->sd);
@@ -484,14 +495,17 @@ static int dw9768_probe(struct i2c_client *client)
 		goto err_power_off;
 	}
 
+	pm_runtime_idle(dev);
+
 	return 0;
 
 err_power_off:
-	if (pm_runtime_enabled(dev))
-		pm_runtime_disable(dev);
-	else
+	if (full_power) {
 		dw9768_runtime_suspend(dev);
+		pm_runtime_set_suspended(dev);
+	}
 err_clean_entity:
+	pm_runtime_disable(dev);
 	media_entity_cleanup(&dw9768->sd.entity);
 err_free_handler:
 	v4l2_ctrl_handler_free(&dw9768->ctrls);
@@ -503,14 +517,17 @@ static int dw9768_remove(struct i2c_client *client)
 {
 	struct v4l2_subdev *sd = i2c_get_clientdata(client);
 	struct dw9768 *dw9768 = sd_to_dw9768(sd);
+	struct device *dev = &client->dev;
 
 	v4l2_async_unregister_subdev(&dw9768->sd);
 	v4l2_ctrl_handler_free(&dw9768->ctrls);
 	media_entity_cleanup(&dw9768->sd.entity);
-	pm_runtime_disable(&client->dev);
-	if (!pm_runtime_status_suspended(&client->dev))
-		dw9768_runtime_suspend(&client->dev);
-	pm_runtime_set_suspended(&client->dev);
+	if ((is_acpi_node(dev_fwnode(dev)) && acpi_dev_state_d0(dev)) ||
+	    (is_of_node(dev_fwnode(dev)) && !pm_runtime_enabled(dev))) {
+		dw9768_runtime_suspend(dev);
+		pm_runtime_set_suspended(dev);
+	}
+	pm_runtime_disable(dev);
 
 	return 0;
 }
-- 
2.30.2