diff mbox series

read ov9281 sensor-id in 2-steps in case the firmware locks

Message ID 918ce2ca-55ff-aff8-ea6c-0c17f566d59d@online.de
State New
Headers show
Series read ov9281 sensor-id in 2-steps in case the firmware locks | expand

Commit Message

Max Schulze Sept. 27, 2023, 8:56 a.m. UTC 
The ov9281 produced by vision-components does not support 
auto-incremented reads, so read the id in 2 separate steps 
to circumvent the error:
  kernel: ov9282 10-0060: chip id mismatch: 9281!=92ff
  kernel: ov9282 10-0060: failed to find sensor: -6


Signed-off-by: Max Schulze <max.schulze@online.de>
Tested-by: Max Schulze <max.schulze@online.de>
Suggested-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
---
This was tested on rpi cm4 with two ov9281 at the same time, 
one from vc, one from inno-maker.

The rpi kernel supported ov9281 out-of-tree until kernel 6.1.
It carried this change originally made by Dave to support the vc
sensor. Switching to mainline now broke support for it.

I could not find a single-commit for the original change to which I 
could link, only squashed ones, i.e.

https://github.com/raspberrypi/linux/commit/eb00efc993d8cd835221255b44e9019a31708abe

 media: i2c: ov9281: Read chip ID via 2 reads

 Vision Components have made an OV9281 module which blocks reading
 back the majority of registers to comply with NDAs, and in doing
 so doesn't allow auto-increment register reading as used when
 reading the chip ID.
---
 drivers/media/i2c/ov9282.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)
diff mbox series

Patch

diff --git a/drivers/media/i2c/ov9282.c b/drivers/media/i2c/ov9282.c
index 068c7449f50e..3b687f6d4581 100644
--- a/drivers/media/i2c/ov9282.c
+++ b/drivers/media/i2c/ov9282.c
@@ -1078,13 +1078,16 @@  static int ov9282_set_stream(struct v4l2_subdev *sd, int enable)
 static int ov9282_detect(struct ov9282 *ov9282)
 {
 	int ret;
-	u32 val;
+	u32 val = 0, id_msb = 0;
 
-	ret = ov9282_read_reg(ov9282, OV9282_REG_ID, 2, &val);
-	if (ret)
-		return ret;
+	// some firmware limits auto-increment register writes, so do it separately
+	ret = ov9282_read_reg(ov9282, OV9282_REG_ID + 1, 1, &val);
+	if (!ret)
+		ret = ov9282_read_reg(ov9282, OV9282_REG_ID, 1, &id_msb);
+
+	val |= (id_msb << 8);
 
-	if (val != OV9282_ID) {
+	if (ret || val != OV9282_ID) {
 		dev_err(ov9282->dev, "chip id mismatch: %x!=%x",
 			OV9282_ID, val);
 		return -ENXIO;