[RFC v4 5/8] media: i2c: ov772x: Force use of SCCB protocol

From: Jacopo Mondi <jacopo@jmondi.org>
To: laurent.pinchart@ideasonboard.com, magnus.damm@gmail.com
Cc: linux-renesas-soc@vger.kernel.org
Subject: [RFC v4 5/8] media: i2c: ov772x: Force use of SCCB protocol
Date: Fri, 19 May 2017 18:02:57 +0200	[thread overview]
Message-ID: <1495209780-27342-6-git-send-email-jacopo@jmondi.org> (raw)
In-Reply-To: <1495209780-27342-1-git-send-email-jacopo@jmondi.org>

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@jmondi.org>
Suggested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 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
