Re: [PATCH v2 2/3] media: i2c: ov772x: Add support for BT656 mode

[Lad, Prabhakar]

Hi Jacopo,

Thank you for the review.

On Thu, Aug 6, 2020 at 3:41 PM Jacopo Mondi <jacopo@xxxxxxxxxx> wrote:
>
> On Mon, Aug 03, 2020 at 12:39:12PM +0100, Lad Prabhakar wrote:
> > Add support to read the bus-type and enable BT656 mode if needed.
> >
> > The driver defaults to parallel mode if bus-type is not specified in DT.
> >
> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> > Reviewed-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> > ---
> >  drivers/media/i2c/ov772x.c | 40 ++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 40 insertions(+)
> >
> > diff --git a/drivers/media/i2c/ov772x.c b/drivers/media/i2c/ov772x.c
> > index 2cc6a678069a..2de9248e3689 100644
> > --- a/drivers/media/i2c/ov772x.c
> > +++ b/drivers/media/i2c/ov772x.c
> > @@ -31,6 +31,7 @@
> >  #include <media/v4l2-ctrls.h>
> >  #include <media/v4l2-device.h>
> >  #include <media/v4l2-event.h>
> > +#include <media/v4l2-fwnode.h>
> >  #include <media/v4l2-image-sizes.h>
> >  #include <media/v4l2-subdev.h>
> >
> > @@ -434,6 +435,7 @@ struct ov772x_priv {
> >  #ifdef CONFIG_MEDIA_CONTROLLER
> >       struct media_pad pad;
> >  #endif
> > +     struct v4l2_fwnode_endpoint ep;
> >  };
> >
> >  /*
> > @@ -574,6 +576,7 @@ static int ov772x_s_stream(struct v4l2_subdev *sd, int enable)
> >  {
> >       struct i2c_client *client = v4l2_get_subdevdata(sd);
> >       struct ov772x_priv *priv = to_ov772x(sd);
> > +     unsigned int val;
> >       int ret = 0;
> >
> >       mutex_lock(&priv->lock);
> > @@ -581,6 +584,22 @@ static int ov772x_s_stream(struct v4l2_subdev *sd, int enable)
> >       if (priv->streaming == enable)
> >               goto done;
> >
> > +     if (priv->ep.bus_type == V4L2_MBUS_BT656 && enable) {
> > +             ret = regmap_read(priv->regmap, COM7, &val);
> > +             if (ret)
> > +                     goto done;
> > +             val |= ITU656_ON_OFF;
> > +             ret = regmap_write(priv->regmap, COM7, val);
> > +     } else if (priv->ep.bus_type == V4L2_MBUS_BT656 && !enable) {
>
> is the !enable intentional ? (sorry I don't have access to the sensor
> manual). If not, see below:
>
> > +             ret = regmap_read(priv->regmap, COM7, &val);
> > +             if (ret)
> > +                     goto done;
> > +             val &= ~ITU656_ON_OFF;
> > +             ret = regmap_write(priv->regmap, COM7, val);
> > +     }
> > +     if (ret)
> > +             goto done;
>
> Could you write this as:
>
Agreed will do.

> static int ov772x_s_stream(struct v4l2_subdev *sd, int enable)
> {
>         struct i2c_client *client = v4l2_get_subdevdata(sd);
>         struct ov772x_priv *priv = to_ov772x(sd);
>         int ret = 0;
>
>         mutex_lock(&priv->lock);
>
>         if (priv->streaming == enable)
>                 goto done;
>
>         if (enable) {
>                 ret = regmap_read(priv->regmap, COM7, &val);
>                 if (ret)
>                         goto done;
>
>                 if (priv->ep.bus_type == V4L2_MBUS_BT656)
>                         val |= ITU656_ON_OFF;
>                 else /* if you accept my suggestion to consider othe
>                         bus types as errors */
>                         val &= ~ITU656_ON_OFF;
>
>                 ret = regmap_write(priv->regmap, COM7, val);
>                 if (ret)
>                         goto done;
>
>                 dev_dbg(&client->dev, "format %d, win %s\n",
>                         priv->cfmt->code, priv->win->name);
>         }
>
>         ret = regmap_update_bits(priv->regmap, COM2, SOFT_SLEEP_MODE,
>                                  enable ? 0 : SOFT_SLEEP_MODE);
>         if (ret)
>                 goto done;
>         priv->streaming = enable;
>
> done:
>         mutex_unlock(&priv->lock);
>
>         return ret;
> }
>
>
> >       ret = regmap_update_bits(priv->regmap, COM2, SOFT_SLEEP_MODE,
> >                                enable ? 0 : SOFT_SLEEP_MODE);
> >       if (ret)
> > @@ -1354,6 +1373,7 @@ static const struct v4l2_subdev_ops ov772x_subdev_ops = {
> >
> >  static int ov772x_probe(struct i2c_client *client)
> >  {
> > +     struct fwnode_handle *endpoint;
> >       struct ov772x_priv      *priv;
> >       int                     ret;
> >       static const struct regmap_config ov772x_regmap_config = {
> > @@ -1415,6 +1435,26 @@ static int ov772x_probe(struct i2c_client *client)
> >               goto error_clk_put;
> >       }
> >
> > +     endpoint = fwnode_graph_get_next_endpoint(dev_fwnode(&client->dev),
> > +                                               NULL);
> > +     if (!endpoint) {
> > +             dev_err(&client->dev, "endpoint node not found\n");
> > +             ret = -EINVAL;
> > +             goto error_clk_put;
> > +     }
> > +
> > +     ret = v4l2_fwnode_endpoint_parse(endpoint, &priv->ep);
> > +     fwnode_handle_put(endpoint);
> > +     if (ret) {
> > +             dev_err(&client->dev, "Could not parse endpoint\n");
> > +             goto error_clk_put;
> > +     }
> > +
> > +     /* fallback to parallel mode */
> > +     if (priv->ep.bus_type != V4L2_MBUS_PARALLEL &&
> > +         priv->ep.bus_type != V4L2_MBUS_BT656)
> > +             priv->ep.bus_type = V4L2_MBUS_PARALLEL;
>
> shouldn't this be an error ? It's either the bus type has not been
> specified on DT (which is fine, otherwise old DTB without that
> properties will fail) and the bus identification routine implemented
> in v4l2_fwnode_endpoint_parse() detected a bus type which is not
> supported, hence the DT properties are wrong, and this should be an
> error. If you plan to expand the parsing routine to support, say
> bus-width and pclk polarity please break this out to a new function.
>
Agreed.

Cheers,
Prabhakar

> Thanks
>    j
>
> > +
> >       ret = ov772x_video_probe(priv);
> >       if (ret < 0)
> >               goto error_gpio_put;
> > --
> > 2.17.1
> >