linux-kernel - Re: [PATCH v5 1/3] media: i2c: ov772x: Parse endpoint properties

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Date:   Wed, 16 Sep 2020 10:30:32 +0200
From:   Jacopo Mondi <jacopo@...ndi.org>
To:     Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Cc:     Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-renesas-soc@...r.kernel.org,
        Biju Das <biju.das.jz@...renesas.com>,
        Prabhakar <prabhakar.csengg@...il.com>
Subject: Re: [PATCH v5 1/3] media: i2c: ov772x: Parse endpoint properties

Hi Prabhakar,
  sorry, two more tiny nits

On Wed, Sep 16, 2020 at 09:47:37AM +0200, Jacopo Mondi wrote:
> Hi Prabhakar,
>
> On Tue, Sep 15, 2020 at 06:42:33PM +0100, Lad Prabhakar wrote:
> > Parse endpoint properties using v4l2_fwnode_endpoint_alloc_parse()
> > to determine bus-type and store it locally in priv data.
> >
> > v4l2_fwnode_endpoint_alloc_parse() with bus_type set to
> > V4L2_MBUS_PARALLEL falls back to V4L2_MBUS_PARALLEL thus handling
> > backward compatibility with existing DT where bus-type isn't specified.
>
>
> I don't think this is necessary here. This patch does not need to
> handle any retrocompatibility, as only PARALLEL is supported.
>
> The 'right' way to put it to me would be
> "Parse endpoint properties using v4l2_fwnode_endpoint_alloc_parse()
> to determine the bus type and store it in the driver structure.
>
> Set bus_type to V4L2_MBUS_PARALLEL as it's the only supported one"
>
> See comment in the next patch for retrocompatibility
>
> >
> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> > ---
> >  drivers/media/i2c/ov772x.c | 25 +++++++++++++++++++++++++
> >  1 file changed, 25 insertions(+)
> >
> > diff --git a/drivers/media/i2c/ov772x.c b/drivers/media/i2c/ov772x.c
> > index 2cc6a678069a..4ab4b3c883d0 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
> > +	enum v4l2_mbus_type		  bus_type;
> >  };
> >
> >  /*
> > @@ -1354,6 +1356,8 @@ static const struct v4l2_subdev_ops ov772x_subdev_ops = {
> >
> >  static int ov772x_probe(struct i2c_client *client)
> >  {
> > +	struct v4l2_fwnode_endpoint bus_cfg;
> > +	struct fwnode_handle	*ep;
> >  	struct ov772x_priv	*priv;
> >  	int			ret;
> >  	static const struct regmap_config ov772x_regmap_config = {
> > @@ -1415,6 +1419,27 @@ static int ov772x_probe(struct i2c_client *client)
> >  		goto error_clk_put;
> >  	}
> >
> > +	ep = fwnode_graph_get_next_endpoint(dev_fwnode(&client->dev),
> > +					    NULL);
> > +	if (!ep) {
> > +		dev_err(&client->dev, "endpoint node not found\n");

Nit: other error messages in the driver start with a capital letter,

> > +		ret = -EINVAL;
> > +		goto error_clk_put;
> > +	}
> > +
> > +	/* For backward compatibility with the existing DT where
> > +	 * bus-type isn't specified v4l2_fwnode_endpoint_alloc_parse()
> > +	 * with bus_type set to V4L2_MBUS_PARALLEL falls back to
> > +	 * V4L2_MBUS_PARALLEL
> > +	 */
>
> You can drop this comment block
>

Or better move it to the next patch. Two nits in the meantime:

Use
        /*
         * This

in place of

        /* This

And I would write it as something like

        /*
         * For backward compatibility with older DTS where the
         * bus-type property was not mandatory, assume
         * V4L2_MBUS_PARALLEL as it was the only supported bus at the
         * time. v4l2_fwnode_endpoint_alloc_parse() will not fail if
         * 'bus-type' is not specified.
         */

Thanks
   j

> > +	bus_cfg.bus_type = V4L2_MBUS_PARALLEL;
> > +	ret = v4l2_fwnode_endpoint_alloc_parse(ep, &bus_cfg);
> > +	priv->bus_type = bus_cfg.bus_type;
>
> Set this after if (ret)
>
> > +	v4l2_fwnode_endpoint_free(&bus_cfg);
> > +	fwnode_handle_put(ep);
> > +	if (ret)
> > +		goto error_clk_put;
> > +
> >  	ret = ov772x_video_probe(priv);
> >  	if (ret < 0)
> >  		goto error_gpio_put;
> > --
> > 2.17.1
> >