linux-kernel - [PATCH v2 3/5] ov5670: Support probe whilst the device is in a low power state

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Message-Id: <20190826083112.8888-4-sakari.ailus@linux.intel.com>
Date:   Mon, 26 Aug 2019 11:31:10 +0300
From:   Sakari Ailus <sakari.ailus@...ux.intel.com>
To:     linux-acpi@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: [PATCH v2 3/5] ov5670: Support probe whilst the device is in a low power state

Tell ACPI device PM code that the driver supports the device being in a
low power state when the driver's probe function is entered.

Signed-off-by: Sakari Ailus <sakari.ailus@...ux.intel.com>
---
 drivers/media/i2c/ov5670.c | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/drivers/media/i2c/ov5670.c b/drivers/media/i2c/ov5670.c
index 041fcbb4eebdf..760fce93337cd 100644
--- a/drivers/media/i2c/ov5670.c
+++ b/drivers/media/i2c/ov5670.c
@@ -2444,6 +2444,7 @@ static int ov5670_probe(struct i2c_client *client)
 	struct ov5670 *ov5670;
 	const char *err_msg;
 	u32 input_clk = 0;
+	bool low_power;
 	int ret;
 
 	device_property_read_u32(&client->dev, "clock-frequency", &input_clk);
@@ -2460,11 +2461,14 @@ static int ov5670_probe(struct i2c_client *client)
 	/* Initialize subdev */
 	v4l2_i2c_subdev_init(&ov5670->sd, client, &ov5670_subdev_ops);
 
-	/* Check module identity */
-	ret = ov5670_identify_module(ov5670);
-	if (ret) {
-		err_msg = "ov5670_identify_module() error";
-		goto error_print;
+	low_power = acpi_dev_low_power_state_probe(&client->dev);
+	if (!low_power) {
+		/* Check module identity */
+		ret = ov5670_identify_module(ov5670);
+		if (ret) {
+			err_msg = "ov5670_identify_module() error";
+			goto error_print;
+		}
 	}
 
 	mutex_init(&ov5670->mutex);
@@ -2501,10 +2505,10 @@ static int ov5670_probe(struct i2c_client *client)
 	ov5670->streaming = false;
 
 	/*
-	 * Device is already turned on by i2c-core with ACPI domain PM.
-	 * Enable runtime PM and turn off the device.
+	 * Don't set the device's state to active if it's in a low power state.
 	 */
-	pm_runtime_set_active(&client->dev);
+	if (!low_power)
+		pm_runtime_set_active(&client->dev);
 	pm_runtime_enable(&client->dev);
 	pm_runtime_idle(&client->dev);
 
@@ -2546,7 +2550,7 @@ static const struct dev_pm_ops ov5670_pm_ops = {
 
 #ifdef CONFIG_ACPI
 static const struct acpi_device_id ov5670_acpi_ids[] = {
-	{"INT3479"},
+	{ "INT3479" },
 	{ /* sentinel */ }
 };
 
@@ -2556,6 +2560,7 @@ MODULE_DEVICE_TABLE(acpi, ov5670_acpi_ids);
 static struct i2c_driver ov5670_i2c_driver = {
 	.driver = {
 		.name = "ov5670",
+		.probe_low_power = true,
 		.pm = &ov5670_pm_ops,
 		.acpi_match_table = ACPI_PTR(ov5670_acpi_ids),
 	},
-- 
2.20.1