Re: [PATCH v2 6/6] media: i2c: ov9282: Fix device detection
From: Sakari Ailus <sakari.ailus@iki.fi>
Date: 2022-07-17 14:22:10
Also in:
linux-media
Hi Alexander, On Fri, Jul 15, 2022 at 09:48:58AM +0200, Alexander Stein wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- 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 + */
I suppose it still works for writes I guess? Would be nice to have this in the comment.
+ ret = ov9282_read_reg(ov9282, OV9282_REG_ID, + 1, &id[0]);
Fits on one line. Same below.
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",-- Sakari Ailus