linux-kernel - [PATCH 1/3] media: i2c: imx219: Fix power sequence

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Message-Id: <20200228165503.18054-2-prabhakar.mahadev-lad.rj@bp.renesas.com>
Date:   Fri, 28 Feb 2020 16:55:01 +0000
From:   Lad Prabhakar <prabhakar.csengg@...il.com>
To:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        Dave Stevenson <dave.stevenson@...pberrypi.com>
Cc:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: [PATCH 1/3] media: i2c: imx219: Fix power sequence

When supporting Rpi Camera v2 Module on the RZ/G2E, found the driver had
some issues with rcar mipi-csi driver. The sesnosr 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 "standby -> streaming -> standby" in the probe().

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@...renesas.com>
---
 drivers/media/i2c/imx219.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/drivers/media/i2c/imx219.c b/drivers/media/i2c/imx219.c
index f1effb5a5f66..8b48e148f2d0 100644
--- a/drivers/media/i2c/imx219.c
+++ b/drivers/media/i2c/imx219.c
@@ -1171,6 +1171,7 @@ static int imx219_check_hwcfg(struct device *dev)
 
 static int imx219_probe(struct i2c_client *client)
 {
+	const struct imx219_reg_list *reg_list;
 	struct device *dev = &client->dev;
 	struct imx219 *imx219;
 	int ret;
@@ -1224,6 +1225,38 @@ static int imx219_probe(struct i2c_client *client)
 	/* Set default mode to max resolution */
 	imx219->mode = &supported_modes[0];
 
+	/* sensor doesn't enter to LP-11 state upon power up until and unless
+	 * streaming is started, so upon power up set the default format and
+	 * switch the modes: standby -> streaming -> standby
+	 */
+	/* getting sensor out of sleep */
+	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);
+
+	reg_list = &imx219->mode->reg_list;
+	ret = imx219_write_regs(imx219, reg_list->regs, reg_list->num_of_regs);
+	if (ret) {
+		dev_err(&client->dev, "%s failed to default mode\n", __func__);
+		goto error_power_off;
+	}
+
+	/* getting sensor out of sleep */
+	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