[PATCH v2 6/6] media: i2c: ov9282: Fix device detection

[Alexander Stein <alexander.stein@ew.tq-group.com>]

Apparently the Vision Components model (VC MIPI OV9281) does not support
address auto-increment, so probe fails with:
ov9282 2-0060: chip id mismatch: 9281!=92ff
Instead do two 1 byte reads and combine the result.

Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
---
Changes in v2:
* Fix commit message
* Add comment about prevented auto-increment
* Return early if reading ID register failed
* Reorder ID registers, smaller register number first

 drivers/media/i2c/ov9282.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/media/i2c/ov9282.c b/drivers/media/i2c/ov9282.c
index 263cdffc558f..532791304c3d 100644
--- a/drivers/media/i2c/ov9282.c
+++ b/drivers/media/i2c/ov9282.c
@@ -761,11 +761,24 @@ static int ov9282_set_stream(struct v4l2_subdev *sd, int enable)
 static int ov9282_detect(struct ov9282 *ov9282)
 {
 	int ret;
+	u32 id[2];
 	u32 val;
 
-	ret = ov9282_read_reg(ov9282, OV9282_REG_ID, 2, &val);
+	/*
+	 * Some vendors prevent auto-increment, so each register has to
+	 * be read separately
+	 */
+	ret = ov9282_read_reg(ov9282, OV9282_REG_ID,
+			      1, &id[0]);
 	if (ret)
 		return ret;
+	ret = ov9282_read_reg(ov9282, OV9282_REG_ID + 1,
+			      1, &id[1]);
+	if (ret)
+		return ret;
+
+	val = id[1];
+	val |= (id[0] << 8);
 
 	if (val != OV9282_ID) {
 		dev_err(ov9282->dev, "chip id mismatch: %x!=%x",
-- 
2.25.1