Commit e78902976150 ("i2c: sh_mobile: don't send a stop condition by
default inside transfers") makes the i2c_sh_mobile I2C-adapter emit a
stop/start sequence between messages in a single transfer only when
explicitly requested with I2C_M_STOP.
This breaks the ov772x driver in the SH4 Migo-R board as the Omnivision
sensor uses the I2C-like SCCB protocol that doesn't support repeated
starts:
i2c-sh_mobile i2c-sh_mobile.0: Transfer request timed out
ov772x 0-0021: Product ID error 92:92
Fix it by marking the client as SCCB, forcing the emission of a
stop/start sequence between all messages.
As I2C_M_STOP requires the I2C adapter to support protocol mangling,
ensure that the I2C_FUNC_PROTOCOL_MANGLING functionality is available.
Tested on SH4 Migo-R board, with OV772x now successfully probing
soc-camera-pdrv soc-camera-pdrv.0: Probing soc-camera-pdrv.0
ov772x 0-0021: ov7725 Product ID 77:21 Manufacturer ID 7f:a2
Signed-off-by: Jacopo Mondi <jacopo@xxxxxxxxxx>
Suggested-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
Acked-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
---
v1 -> v2:
- change commit message to describe what this fix is for first.
v2 -> v3:
- add to commit message that patch checks for I2C_FUNC_PROTOCOL_MANGLING support
drivers/media/i2c/soc_camera/ov772x.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/media/i2c/soc_camera/ov772x.c b/drivers/media/i2c/soc_camera/ov772x.c
index 985a367..351abec 100644
--- a/drivers/media/i2c/soc_camera/ov772x.c
+++ b/drivers/media/i2c/soc_camera/ov772x.c
@@ -1062,11 +1062,13 @@ static int ov772x_probe(struct i2c_client *client,
return -EINVAL;
}
- if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) {
+ if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
+ I2C_FUNC_PROTOCOL_MANGLING)) {
dev_err(&adapter->dev,
- "I2C-Adapter doesn't support I2C_FUNC_SMBUS_BYTE_DATA\n");
+ "I2C-Adapter doesn't support SMBUS_BYTE_DATA or PROTOCOL_MANGLING\n");
return -EIO;
}
+ client->flags |= I2C_CLIENT_SCCB;
priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
--
2.7.4
