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

Hi Jacopo,

Thank you for the review.

On Thu, Aug 6, 2020 at 3:41 PM Jacopo Mondi [off-list ref] wrote:

On Mon, Aug 03, 2020 at 12:39:12PM +0100, Lad Prabhakar wrote:

quoted

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@bp.renesas.com>
Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
---
 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:

quoted

+             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;
}

quoted

      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

quoted

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