| Message ID | 1523116090-13101-2-git-send-email-akinobu.mita@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hello Akinobu,
thank you for the patch.
On which platform have you tested the series (just curious) ?
On Sun, Apr 08, 2018 at 12:48:05AM +0900, Akinobu Mita wrote:
> The ov772x driver only works when the i2c controller have
> I2C_FUNC_PROTOCOL_MANGLING. However, many i2c controller drivers don't
> support it.
>
> The reason that the ov772x requires I2C_FUNC_PROTOCOL_MANGLING is that
> it doesn't support repeated starts.
>
> This change adds an alternative method for reading from ov772x register
> which uses two separated i2c messages for the i2c controllers without
> I2C_FUNC_PROTOCOL_MANGLING.
Actually, and please correct me if I'm wrong, what I see here is that
an i2c_master_send+i2c_master_recv sequence is equivalent to a mangled
smbus transaction:
i2c_smbus_read_byte_data | I2C_CLIENT_SCCB:
S Addr Wr [A] Comm [A] P S Addr Rd [A] [Data] NA P
i2c_master_send() + i2c_master_recv():
S Addr Wr [A] Data [A] P
S Addr Rd [A] [Data] NA P
I wonder if it is not worth to ditch the existing read() function in
favour of your new proposed one completely.
I have tested it on the Migo-R board where I have an ov772x installed
and it works fine.
Although I would like to have a confirmation this is fine by people
how has seen more i2c adapters in action than me :)
Thanks
j
>
> Cc: Jacopo Mondi <jacopo+renesas@jmondi.org>
> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Cc: Hans Verkuil <hans.verkuil@cisco.com>
> Cc: Sakari Ailus <sakari.ailus@linux.intel.com>
> Cc: Mauro Carvalho Chehab <mchehab@s-opensource.com>
> Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
> ---
> drivers/media/i2c/ov772x.c | 42 +++++++++++++++++++++++++++++++++---------
> 1 file changed, 33 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/media/i2c/ov772x.c b/drivers/media/i2c/ov772x.c
> index b62860c..283ae2c 100644
> --- a/drivers/media/i2c/ov772x.c
> +++ b/drivers/media/i2c/ov772x.c
> @@ -424,6 +424,7 @@ struct ov772x_priv {
> /* band_filter = COM8[5] ? 256 - BDBASE : 0 */
> unsigned short band_filter;
> unsigned int fps;
> + int (*reg_read)(struct i2c_client *client, u8 addr);
> };
>
> /*
> @@ -542,11 +543,34 @@ static struct ov772x_priv *to_ov772x(struct v4l2_subdev *sd)
> return container_of(sd, struct ov772x_priv, subdev);
> }
>
> -static inline int ov772x_read(struct i2c_client *client, u8 addr)
> +static int ov772x_read(struct i2c_client *client, u8 addr)
> +{
> + struct v4l2_subdev *sd = i2c_get_clientdata(client);
> + struct ov772x_priv *priv = to_ov772x(sd);
> +
> + return priv->reg_read(client, addr);
> +}
> +
> +static int ov772x_reg_read(struct i2c_client *client, u8 addr)
> {
> return i2c_smbus_read_byte_data(client, addr);
> }
>
> +static int ov772x_reg_read_fallback(struct i2c_client *client, u8 addr)
> +{
> + int ret;
> + u8 val;
> +
> + ret = i2c_master_send(client, &addr, 1);
> + if (ret < 0)
> + return ret;
> + ret = i2c_master_recv(client, &val, 1);
> + if (ret < 0)
> + return ret;
> +
> + return val;
> +}
> +
> static inline int ov772x_write(struct i2c_client *client, u8 addr, u8 value)
> {
> return i2c_smbus_write_byte_data(client, addr, value);
> @@ -1255,20 +1279,20 @@ static int ov772x_probe(struct i2c_client *client,
> return -EINVAL;
> }
>
> - if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
> - I2C_FUNC_PROTOCOL_MANGLING)) {
> - dev_err(&adapter->dev,
> - "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)
> return -ENOMEM;
>
> priv->info = client->dev.platform_data;
>
> + if (i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
> + I2C_FUNC_PROTOCOL_MANGLING))
> + priv->reg_read = ov772x_reg_read;
> + else
> + priv->reg_read = ov772x_reg_read_fallback;
> +
> + client->flags |= I2C_CLIENT_SCCB;
> +
> v4l2_i2c_subdev_init(&priv->subdev, client, &ov772x_subdev_ops);
> v4l2_ctrl_handler_init(&priv->hdl, 3);
> v4l2_ctrl_new_std(&priv->hdl, &ov772x_ctrl_ops,
> --
> 2.7.4
>
Hello, On Monday, 9 April 2018 09:58:12 EEST jacopo mondi wrote: > Hello Akinobu, > thank you for the patch. > > On which platform have you tested the series (just curious) ? > > On Sun, Apr 08, 2018 at 12:48:05AM +0900, Akinobu Mita wrote: > > The ov772x driver only works when the i2c controller have > > I2C_FUNC_PROTOCOL_MANGLING. However, many i2c controller drivers don't > > support it. > > > > The reason that the ov772x requires I2C_FUNC_PROTOCOL_MANGLING is that > > it doesn't support repeated starts. > > > > This change adds an alternative method for reading from ov772x register > > which uses two separated i2c messages for the i2c controllers without > > I2C_FUNC_PROTOCOL_MANGLING. > > Actually, and please correct me if I'm wrong, what I see here is that > an i2c_master_send+i2c_master_recv sequence is equivalent to a mangled > smbus transaction: > > i2c_smbus_read_byte_data | I2C_CLIENT_SCCB: > S Addr Wr [A] Comm [A] P S Addr Rd [A] [Data] NA P > > i2c_master_send() + i2c_master_recv(): > S Addr Wr [A] Data [A] P > S Addr Rd [A] [Data] NA P > > I wonder if it is not worth to ditch the existing read() function in > favour of your new proposed one completely. Given that this implementation is in no way specific to the ov772x driver, wouldn't it be better to handle this fallback in the I2C core instead ? > I have tested it on the Migo-R board where I have an ov772x installed > and it works fine. > > Although I would like to have a confirmation this is fine by people > how has seen more i2c adapters in action than me :) > > > Cc: Jacopo Mondi <jacopo+renesas@jmondi.org> > > Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com> > > Cc: Hans Verkuil <hans.verkuil@cisco.com> > > Cc: Sakari Ailus <sakari.ailus@linux.intel.com> > > Cc: Mauro Carvalho Chehab <mchehab@s-opensource.com> > > Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> > > --- > > > > drivers/media/i2c/ov772x.c | 42 ++++++++++++++++++++++++++++++++--------- > > 1 file changed, 33 insertions(+), 9 deletions(-) > > > > diff --git a/drivers/media/i2c/ov772x.c b/drivers/media/i2c/ov772x.c > > index b62860c..283ae2c 100644 > > --- a/drivers/media/i2c/ov772x.c > > +++ b/drivers/media/i2c/ov772x.c > > @@ -424,6 +424,7 @@ struct ov772x_priv { > > /* band_filter = COM8[5] ? 256 - BDBASE : 0 */ > > unsigned short band_filter; > > unsigned int fps; > > + int (*reg_read)(struct i2c_client *client, u8 addr); > > }; > > > > /* > > @@ -542,11 +543,34 @@ static struct ov772x_priv *to_ov772x(struct > > v4l2_subdev *sd) > > return container_of(sd, struct ov772x_priv, subdev); > > } > > > > -static inline int ov772x_read(struct i2c_client *client, u8 addr) > > +static int ov772x_read(struct i2c_client *client, u8 addr) > > +{ > > + struct v4l2_subdev *sd = i2c_get_clientdata(client); > > + struct ov772x_priv *priv = to_ov772x(sd); > > + > > + return priv->reg_read(client, addr); > > +} > > + > > +static int ov772x_reg_read(struct i2c_client *client, u8 addr) > > { > > return i2c_smbus_read_byte_data(client, addr); > > } > > > > +static int ov772x_reg_read_fallback(struct i2c_client *client, u8 addr) > > +{ > > + int ret; > > + u8 val; > > + > > + ret = i2c_master_send(client, &addr, 1); > > + if (ret < 0) > > + return ret; > > + ret = i2c_master_recv(client, &val, 1); > > + if (ret < 0) > > + return ret; > > + > > + return val; > > +} > > + > > > > static inline int ov772x_write(struct i2c_client *client, u8 addr, u8 > > value) { > > return i2c_smbus_write_byte_data(client, addr, value); > > @@ -1255,20 +1279,20 @@ static int ov772x_probe(struct i2c_client *client, > > return -EINVAL; > > } > > > > - if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA | > > - I2C_FUNC_PROTOCOL_MANGLING)) { > > - dev_err(&adapter->dev, > > - "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) > > return -ENOMEM; > > > > priv->info = client->dev.platform_data; > > > > + if (i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA | > > + I2C_FUNC_PROTOCOL_MANGLING)) > > + priv->reg_read = ov772x_reg_read; > > + else > > + priv->reg_read = ov772x_reg_read_fallback; > > + > > + client->flags |= I2C_CLIENT_SCCB; > > + > > v4l2_i2c_subdev_init(&priv->subdev, client, &ov772x_subdev_ops); > > v4l2_ctrl_handler_init(&priv->hdl, 3); > > v4l2_ctrl_new_std(&priv->hdl, &ov772x_ctrl_ops,
2018-04-09 15:58 GMT+09:00 jacopo mondi <jacopo@jmondi.org>: > Hello Akinobu, > thank you for the patch. > > On which platform have you tested the series (just curious) ? I use Zynq-7000 development board with Xilinx Video IP driver and custom video pipeline design based on the example reference project. > On Sun, Apr 08, 2018 at 12:48:05AM +0900, Akinobu Mita wrote: >> The ov772x driver only works when the i2c controller have >> I2C_FUNC_PROTOCOL_MANGLING. However, many i2c controller drivers don't >> support it. >> >> The reason that the ov772x requires I2C_FUNC_PROTOCOL_MANGLING is that >> it doesn't support repeated starts. >> >> This change adds an alternative method for reading from ov772x register >> which uses two separated i2c messages for the i2c controllers without >> I2C_FUNC_PROTOCOL_MANGLING. > > Actually, and please correct me if I'm wrong, what I see here is that > an i2c_master_send+i2c_master_recv sequence is equivalent to a mangled > smbus transaction: > > i2c_smbus_read_byte_data | I2C_CLIENT_SCCB: > S Addr Wr [A] Comm [A] P S Addr Rd [A] [Data] NA P > > i2c_master_send() + i2c_master_recv(): > S Addr Wr [A] Data [A] P > S Addr Rd [A] [Data] NA P > > I wonder if it is not worth to ditch the existing read() function in > favour of your new proposed one completely. > > I have tested it on the Migo-R board where I have an ov772x installed > and it works fine. I'll replace the read() function to the new implementation in the next version of this patchset. Although handling in the I2C core is fascinating, I feel the area of influence is a bit large. > Although I would like to have a confirmation this is fine by people > how has seen more i2c adapters in action than me :) > > Thanks > j > >> >> Cc: Jacopo Mondi <jacopo+renesas@jmondi.org> >> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com> >> Cc: Hans Verkuil <hans.verkuil@cisco.com> >> Cc: Sakari Ailus <sakari.ailus@linux.intel.com> >> Cc: Mauro Carvalho Chehab <mchehab@s-opensource.com> >> Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> >> --- >> drivers/media/i2c/ov772x.c | 42 +++++++++++++++++++++++++++++++++--------- >> 1 file changed, 33 insertions(+), 9 deletions(-) >> >> diff --git a/drivers/media/i2c/ov772x.c b/drivers/media/i2c/ov772x.c >> index b62860c..283ae2c 100644 >> --- a/drivers/media/i2c/ov772x.c >> +++ b/drivers/media/i2c/ov772x.c >> @@ -424,6 +424,7 @@ struct ov772x_priv { >> /* band_filter = COM8[5] ? 256 - BDBASE : 0 */ >> unsigned short band_filter; >> unsigned int fps; >> + int (*reg_read)(struct i2c_client *client, u8 addr); >> }; >> >> /* >> @@ -542,11 +543,34 @@ static struct ov772x_priv *to_ov772x(struct v4l2_subdev *sd) >> return container_of(sd, struct ov772x_priv, subdev); >> } >> >> -static inline int ov772x_read(struct i2c_client *client, u8 addr) >> +static int ov772x_read(struct i2c_client *client, u8 addr) >> +{ >> + struct v4l2_subdev *sd = i2c_get_clientdata(client); >> + struct ov772x_priv *priv = to_ov772x(sd); >> + >> + return priv->reg_read(client, addr); >> +} >> + >> +static int ov772x_reg_read(struct i2c_client *client, u8 addr) >> { >> return i2c_smbus_read_byte_data(client, addr); >> } >> >> +static int ov772x_reg_read_fallback(struct i2c_client *client, u8 addr) >> +{ >> + int ret; >> + u8 val; >> + >> + ret = i2c_master_send(client, &addr, 1); >> + if (ret < 0) >> + return ret; >> + ret = i2c_master_recv(client, &val, 1); >> + if (ret < 0) >> + return ret; >> + >> + return val; >> +} >> + >> static inline int ov772x_write(struct i2c_client *client, u8 addr, u8 value) >> { >> return i2c_smbus_write_byte_data(client, addr, value); >> @@ -1255,20 +1279,20 @@ static int ov772x_probe(struct i2c_client *client, >> return -EINVAL; >> } >> >> - if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA | >> - I2C_FUNC_PROTOCOL_MANGLING)) { >> - dev_err(&adapter->dev, >> - "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) >> return -ENOMEM; >> >> priv->info = client->dev.platform_data; >> >> + if (i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA | >> + I2C_FUNC_PROTOCOL_MANGLING)) >> + priv->reg_read = ov772x_reg_read; >> + else >> + priv->reg_read = ov772x_reg_read_fallback; >> + >> + client->flags |= I2C_CLIENT_SCCB; >> + >> v4l2_i2c_subdev_init(&priv->subdev, client, &ov772x_subdev_ops); >> v4l2_ctrl_handler_init(&priv->hdl, 3); >> v4l2_ctrl_new_std(&priv->hdl, &ov772x_ctrl_ops, >> -- >> 2.7.4 >>
Hi Akinobu, On Wed, Apr 11, 2018 at 01:37:03AM +0900, Akinobu Mita wrote: > 2018-04-09 15:58 GMT+09:00 jacopo mondi <jacopo@jmondi.org>: > > Hello Akinobu, > > thank you for the patch. > > > > On which platform have you tested the series (just curious) ? > > I use Zynq-7000 development board with Xilinx Video IP driver and > custom video pipeline design based on the example reference project. > That's interesting! I was just wondering if there were other development boards around that ship with this sensor... > > On Sun, Apr 08, 2018 at 12:48:05AM +0900, Akinobu Mita wrote: > >> The ov772x driver only works when the i2c controller have > >> I2C_FUNC_PROTOCOL_MANGLING. However, many i2c controller drivers don't > >> support it. > >> > >> The reason that the ov772x requires I2C_FUNC_PROTOCOL_MANGLING is that > >> it doesn't support repeated starts. > >> > >> This change adds an alternative method for reading from ov772x register > >> which uses two separated i2c messages for the i2c controllers without > >> I2C_FUNC_PROTOCOL_MANGLING. > > > > Actually, and please correct me if I'm wrong, what I see here is that > > an i2c_master_send+i2c_master_recv sequence is equivalent to a mangled > > smbus transaction: > > > > i2c_smbus_read_byte_data | I2C_CLIENT_SCCB: > > S Addr Wr [A] Comm [A] P S Addr Rd [A] [Data] NA P > > > > i2c_master_send() + i2c_master_recv(): > > S Addr Wr [A] Data [A] P > > S Addr Rd [A] [Data] NA P > > > > I wonder if it is not worth to ditch the existing read() function in > > favour of your new proposed one completely. > > > > I have tested it on the Migo-R board where I have an ov772x installed > > and it works fine. > > I'll replace the read() function to the new implementation in the next > version of this patchset. Although handling in the I2C core is fascinating, > I feel the area of influence is a bit large. > Yep, i2c is huge and complex but fascinating, and the SCCB use case should probably be handled with a master_send+master_read instead of relying on the i2c adapter ability to send an additional stop bit in between an smbus transaction, as Laurent suggested. I wonder why it has not been implemented this way from day 1. I'm sure there are reasons :) I'll wait for v2. Thanks j > > Although I would like to have a confirmation this is fine by people > > how has seen more i2c adapters in action than me :) > > > > Thanks > > j > > > >> > >> Cc: Jacopo Mondi <jacopo+renesas@jmondi.org> > >> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com> > >> Cc: Hans Verkuil <hans.verkuil@cisco.com> > >> Cc: Sakari Ailus <sakari.ailus@linux.intel.com> > >> Cc: Mauro Carvalho Chehab <mchehab@s-opensource.com> > >> Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> > >> --- > >> drivers/media/i2c/ov772x.c | 42 +++++++++++++++++++++++++++++++++--------- > >> 1 file changed, 33 insertions(+), 9 deletions(-) > >> > >> diff --git a/drivers/media/i2c/ov772x.c b/drivers/media/i2c/ov772x.c > >> index b62860c..283ae2c 100644 > >> --- a/drivers/media/i2c/ov772x.c > >> +++ b/drivers/media/i2c/ov772x.c > >> @@ -424,6 +424,7 @@ struct ov772x_priv { > >> /* band_filter = COM8[5] ? 256 - BDBASE : 0 */ > >> unsigned short band_filter; > >> unsigned int fps; > >> + int (*reg_read)(struct i2c_client *client, u8 addr); > >> }; > >> > >> /* > >> @@ -542,11 +543,34 @@ static struct ov772x_priv *to_ov772x(struct v4l2_subdev *sd) > >> return container_of(sd, struct ov772x_priv, subdev); > >> } > >> > >> -static inline int ov772x_read(struct i2c_client *client, u8 addr) > >> +static int ov772x_read(struct i2c_client *client, u8 addr) > >> +{ > >> + struct v4l2_subdev *sd = i2c_get_clientdata(client); > >> + struct ov772x_priv *priv = to_ov772x(sd); > >> + > >> + return priv->reg_read(client, addr); > >> +} > >> + > >> +static int ov772x_reg_read(struct i2c_client *client, u8 addr) > >> { > >> return i2c_smbus_read_byte_data(client, addr); > >> } > >> > >> +static int ov772x_reg_read_fallback(struct i2c_client *client, u8 addr) > >> +{ > >> + int ret; > >> + u8 val; > >> + > >> + ret = i2c_master_send(client, &addr, 1); > >> + if (ret < 0) > >> + return ret; > >> + ret = i2c_master_recv(client, &val, 1); > >> + if (ret < 0) > >> + return ret; > >> + > >> + return val; > >> +} > >> + > >> static inline int ov772x_write(struct i2c_client *client, u8 addr, u8 value) > >> { > >> return i2c_smbus_write_byte_data(client, addr, value); > >> @@ -1255,20 +1279,20 @@ static int ov772x_probe(struct i2c_client *client, > >> return -EINVAL; > >> } > >> > >> - if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA | > >> - I2C_FUNC_PROTOCOL_MANGLING)) { > >> - dev_err(&adapter->dev, > >> - "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) > >> return -ENOMEM; > >> > >> priv->info = client->dev.platform_data; > >> > >> + if (i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA | > >> + I2C_FUNC_PROTOCOL_MANGLING)) > >> + priv->reg_read = ov772x_reg_read; > >> + else > >> + priv->reg_read = ov772x_reg_read_fallback; > >> + > >> + client->flags |= I2C_CLIENT_SCCB; > >> + > >> v4l2_i2c_subdev_init(&priv->subdev, client, &ov772x_subdev_ops); > >> v4l2_ctrl_handler_init(&priv->hdl, 3); > >> v4l2_ctrl_new_std(&priv->hdl, &ov772x_ctrl_ops, > >> -- > >> 2.7.4 > >>
diff --git a/drivers/media/i2c/ov772x.c b/drivers/media/i2c/ov772x.c index b62860c..283ae2c 100644 --- a/drivers/media/i2c/ov772x.c +++ b/drivers/media/i2c/ov772x.c @@ -424,6 +424,7 @@ struct ov772x_priv { /* band_filter = COM8[5] ? 256 - BDBASE : 0 */ unsigned short band_filter; unsigned int fps; + int (*reg_read)(struct i2c_client *client, u8 addr); }; /* @@ -542,11 +543,34 @@ static struct ov772x_priv *to_ov772x(struct v4l2_subdev *sd) return container_of(sd, struct ov772x_priv, subdev); } -static inline int ov772x_read(struct i2c_client *client, u8 addr) +static int ov772x_read(struct i2c_client *client, u8 addr) +{ + struct v4l2_subdev *sd = i2c_get_clientdata(client); + struct ov772x_priv *priv = to_ov772x(sd); + + return priv->reg_read(client, addr); +} + +static int ov772x_reg_read(struct i2c_client *client, u8 addr) { return i2c_smbus_read_byte_data(client, addr); } +static int ov772x_reg_read_fallback(struct i2c_client *client, u8 addr) +{ + int ret; + u8 val; + + ret = i2c_master_send(client, &addr, 1); + if (ret < 0) + return ret; + ret = i2c_master_recv(client, &val, 1); + if (ret < 0) + return ret; + + return val; +} + static inline int ov772x_write(struct i2c_client *client, u8 addr, u8 value) { return i2c_smbus_write_byte_data(client, addr, value); @@ -1255,20 +1279,20 @@ static int ov772x_probe(struct i2c_client *client, return -EINVAL; } - if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA | - I2C_FUNC_PROTOCOL_MANGLING)) { - dev_err(&adapter->dev, - "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) return -ENOMEM; priv->info = client->dev.platform_data; + if (i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA | + I2C_FUNC_PROTOCOL_MANGLING)) + priv->reg_read = ov772x_reg_read; + else + priv->reg_read = ov772x_reg_read_fallback; + + client->flags |= I2C_CLIENT_SCCB; + v4l2_i2c_subdev_init(&priv->subdev, client, &ov772x_subdev_ops); v4l2_ctrl_handler_init(&priv->hdl, 3); v4l2_ctrl_new_std(&priv->hdl, &ov772x_ctrl_ops,
The ov772x driver only works when the i2c controller have I2C_FUNC_PROTOCOL_MANGLING. However, many i2c controller drivers don't support it. The reason that the ov772x requires I2C_FUNC_PROTOCOL_MANGLING is that it doesn't support repeated starts. This change adds an alternative method for reading from ov772x register which uses two separated i2c messages for the i2c controllers without I2C_FUNC_PROTOCOL_MANGLING. Cc: Jacopo Mondi <jacopo+renesas@jmondi.org> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Cc: Hans Verkuil <hans.verkuil@cisco.com> Cc: Sakari Ailus <sakari.ailus@linux.intel.com> Cc: Mauro Carvalho Chehab <mchehab@s-opensource.com> Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> --- drivers/media/i2c/ov772x.c | 42 +++++++++++++++++++++++++++++++++--------- 1 file changed, 33 insertions(+), 9 deletions(-)