[RFC PATCH V7 1/3] media: platform: mtk-isp: Add Mediatek sensor interface driver

[Chun-Kuang Hu]

Hi, Louis:

Louis Kuo <louis.kuo at mediatek.com> 於 2020年7月8日 週三 下午6:41寫道：
>
> This patch adds Mediatek's sensor interface driver. Sensor interface
> driver is a MIPI-CSI2 host driver, namely, a HW camera interface controller.
> It support a widely adopted, simple, high-speed protocol primarily intended
> for point-to-point image and video transmission between cameras and host
> devices. The mtk-isp directory will contain drivers for multiple IP blocks
> found in Mediatek ISP system. It will include ISP Pass 1 driver, sensor
> interface driver, DIP driver and face detection driver.
>
> Signed-off-by: Louis Kuo <louis.kuo at mediatek.com>
> ---

[snip]

> +
> +enum CFG_CSI_PORT {
> +       CFG_CSI_PORT_0 = 0x0,   /* 4D1C */
> +       CFG_CSI_PORT_1,         /* 4D1C */
> +       CFG_CSI_PORT_2,         /* 4D1C */
> +       CFG_CSI_PORT_0A,        /* 2D1C */
> +       CFG_CSI_PORT_0B,        /* 2D1C */
> +       CFG_CSI_PORT_MAX_NUM,
> +       CFG_CSI_PORT_NONE       /*for non-MIPI sensor */
> +};
> +
> +enum PIXEL_MODE {
> +       ONE_PIXEL_MODE  = 0x0,
> +       TWO_PIXEL_MODE  = 0x1,
> +       FOUR_PIXEL_MODE = 0x2,
> +};
> +
> +enum SENINF_ID {
> +       SENINF_1 = 0x0,
> +       SENINF_2 = 0x1,
> +       SENINF_3 = 0x2,
> +       SENINF_4 = 0x3,
> +       SENINF_5 = 0x4,
> +       SENINF_NUM,
> +};
> +

[snip]

> +
> +static int seninf_link_setup(struct media_entity *entity,
> +                            const struct media_pad *local,
> +                            const struct media_pad *remote, u32 flags)
> +{
> +       struct v4l2_subdev *sd;
> +       struct mtk_seninf *priv;
> +       struct device *dev;
> +
> +       sd = media_entity_to_v4l2_subdev(entity);
> +       priv = v4l2_get_subdevdata(sd);
> +       dev = priv->dev;
> +
> +       if (!(flags & MEDIA_LNK_FL_ENABLED))
> +               return 0;
> +
> +       if (local->flags & MEDIA_PAD_FL_SOURCE) {
> +               priv->mux_sel = local->index - CAM_MUX_IDX_MIN;
> +       } else {
> +               /* Select port */
> +               priv->port = local->index;

I don't understand V4L2 much, but the port definition is inside this
file, how does the caller know what to pass to here? Could you explain
how does it work?

Regards,
Chun-Kuang.

> +               if (priv->port >= NUM_SENSORS) {
> +                       dev_err(dev, "port index is over number of ports\n");
> +                       return -EINVAL;
> +               }
> +       }
> +
> +       return 0;
> +}
> +