[PATCH v2 1/3] media: i2c: imx219: Fix power sequence

[Lad Prabhakar <prabhakar.csengg@gmail.com>]

When supporting Rpi Camera v2 Module on the RZ/G2E, found the driver had
some issues with rcar mipi-csi driver. The sensor never entered into LP-11
state.

The powerup sequence in the datasheet[1] shows the sensor entering into
LP-11 in streaming mode, so to fix this issue transitions are performed
from "streaming -> standby" in the probe() after power up.

With this commit the sensor is able to enter LP-11 mode during power up,
as expected by some CSI-2 controllers.

[1] https://publiclab.org/system/images/photos/000/023/294/original/
RASPBERRY_PI_CAMERA_V2_DATASHEET_IMX219PQH5_7.0.0_Datasheet_XXX.PDF

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
---
 drivers/media/i2c/imx219.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/media/i2c/imx219.c b/drivers/media/i2c/imx219.c
index f1effb5a5f66..16010ca1781a 100644
--- a/drivers/media/i2c/imx219.c
+++ b/drivers/media/i2c/imx219.c
@@ -1224,6 +1224,23 @@ static int imx219_probe(struct i2c_client *client)
 	/* Set default mode to max resolution */
 	imx219->mode = &supported_modes[0];
 
+	/* sensor doesn't enter LP-11 state upon power up until and unless
+	 * streaming is started, so upon power up switch the modes to:
+	 * streaming -> standby
+	 */
+	ret = imx219_write_reg(imx219, IMX219_REG_MODE_SELECT,
+			       IMX219_REG_VALUE_08BIT, IMX219_MODE_STREAMING);
+	if (ret < 0)
+		goto error_power_off;
+	usleep_range(100, 110);
+
+	/* put sensor back to standby mode */
+	ret = imx219_write_reg(imx219, IMX219_REG_MODE_SELECT,
+			       IMX219_REG_VALUE_08BIT, IMX219_MODE_STANDBY);
+	if (ret < 0)
+		goto error_power_off;
+	usleep_range(100, 110);
+
 	ret = imx219_init_controls(imx219);
 	if (ret)
 		goto error_power_off;
-- 
2.20.1