[PATCH 4/6] media: imx208: Support device probe in non-zero ACPI D state

[Bingbu Cao <bingbu.cao@xxxxxxxxx>]

Tell ACPI device PM code that the driver supports the device being in
non-zero ACPI D state when the driver's probe function is entered.

Also do identification on the first access of the device, whether in probe
or when starting streaming.

Signed-off-by: Bingbu Cao <bingbu.cao@xxxxxxxxx>
---
 drivers/media/i2c/imx208.c | 77 +++++++++++++++++++++++++++++-----------------
 1 file changed, 48 insertions(+), 29 deletions(-)

diff --git a/drivers/media/i2c/imx208.c b/drivers/media/i2c/imx208.c
index 6f3d9c1b5879..b9f6d5f33b58 100644
--- a/drivers/media/i2c/imx208.c
+++ b/drivers/media/i2c/imx208.c
@@ -296,6 +296,9 @@ struct imx208 {
 	/* OTP data */
 	bool otp_read;
 	char otp_data[IMX208_OTP_SIZE];
+
+	/* True if the device has been identified */
+	bool identified;
 };
 
 static inline struct imx208 *to_imx208(struct v4l2_subdev *_sd)
@@ -619,6 +622,34 @@ static int imx208_set_pad_format(struct v4l2_subdev *sd,
 	return 0;
 }
 
+static int imx208_identify_module(struct imx208 *imx208)
+{
+	struct i2c_client *client = v4l2_get_subdevdata(&imx208->sd);
+	int ret;
+	u32 val;
+
+	if (imx208->identified)
+		return 0;
+
+	ret = imx208_read_reg(imx208, IMX208_REG_CHIP_ID,
+			      2, &val);
+	if (ret) {
+		dev_err(&client->dev, "failed to read chip id %x\n",
+			IMX208_CHIP_ID);
+		return ret;
+	}
+
+	if (val != IMX208_CHIP_ID) {
+		dev_err(&client->dev, "chip id mismatch: %x!=%x\n",
+			IMX208_CHIP_ID, val);
+		return -EIO;
+	}
+
+	imx208->identified = true;
+
+	return 0;
+}
+
 /* Start streaming */
 static int imx208_start_streaming(struct imx208 *imx208)
 {
@@ -626,6 +657,10 @@ static int imx208_start_streaming(struct imx208 *imx208)
 	const struct imx208_reg_list *reg_list;
 	int ret, link_freq_index;
 
+	ret = imx208_identify_module(imx208);
+	if (ret)
+		return ret;
+
 	/* Setup PLL */
 	link_freq_index = imx208->cur_mode->link_freq_index;
 	reg_list = &link_freq_configs[link_freq_index].reg_list;
@@ -752,29 +787,6 @@ static int __maybe_unused imx208_resume(struct device *dev)
 }
 
 /* Verify chip ID */
-static int imx208_identify_module(struct imx208 *imx208)
-{
-	struct i2c_client *client = v4l2_get_subdevdata(&imx208->sd);
-	int ret;
-	u32 val;
-
-	ret = imx208_read_reg(imx208, IMX208_REG_CHIP_ID,
-			      2, &val);
-	if (ret) {
-		dev_err(&client->dev, "failed to read chip id %x\n",
-			IMX208_CHIP_ID);
-		return ret;
-	}
-
-	if (val != IMX208_CHIP_ID) {
-		dev_err(&client->dev, "chip id mismatch: %x!=%x\n",
-			IMX208_CHIP_ID, val);
-		return -EIO;
-	}
-
-	return 0;
-}
-
 static const struct v4l2_subdev_video_ops imx208_video_ops = {
 	.s_stream = imx208_set_stream,
 };
@@ -961,6 +973,7 @@ static int imx208_probe(struct i2c_client *client)
 {
 	struct imx208 *imx208;
 	int ret;
+	bool full_power;
 	u32 val = 0;
 
 	device_property_read_u32(&client->dev, "clock-frequency", &val);
@@ -978,11 +991,14 @@ static int imx208_probe(struct i2c_client *client)
 	/* Initialize subdev */
 	v4l2_i2c_subdev_init(&imx208->sd, client, &imx208_subdev_ops);
 
-	/* Check module identity */
-	ret = imx208_identify_module(imx208);
-	if (ret) {
-		dev_err(&client->dev, "failed to find sensor: %d", ret);
-		goto error_probe;
+	full_power = acpi_dev_state_d0(&client->dev);
+	if (full_power) {
+		/* Check module identity */
+		ret = imx208_identify_module(imx208);
+		if (ret) {
+			dev_err(&client->dev, "failed to find sensor: %d", ret);
+			goto error_probe;
+		}
 	}
 
 	/* Set default mode to max resolution */
@@ -1017,7 +1033,9 @@ static int imx208_probe(struct i2c_client *client)
 		goto error_async_subdev;
 	}
 
-	pm_runtime_set_active(&client->dev);
+	/* Set the device's state to active if it's in D0 state. */
+	if (full_power)
+		pm_runtime_set_active(&client->dev);
 	pm_runtime_enable(&client->dev);
 	pm_runtime_idle(&client->dev);
 
@@ -1077,6 +1095,7 @@ static struct i2c_driver imx208_i2c_driver = {
 	},
 	.probe_new = imx208_probe,
 	.remove = imx208_remove,
+	.flags = I2C_DRV_ACPI_WAIVE_D0_PROBE,
 };
 
 module_i2c_driver(imx208_i2c_driver);
-- 
2.7.4