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References: <20220709135052.3850913-1-aford173@gmail.com> <20220709135052.3850913-2-aford173@gmail.com>
In-Reply-To: <20220709135052.3850913-2-aford173@gmail.com>
From:   Dave Stevenson <dave.stevenson@raspberrypi.com>
Date:   Wed, 27 Jul 2022 15:30:21 +0100
Message-ID: <CAPY8ntA-KBfJwgxtsHdG32wA+v518=r5NBNbHZqFgEC7fp5xUA@mail.gmail.com>
Subject: Re: [PATCH 2/2] media: i2c: imx219: Support four-lane operation
To:     Adam Ford <aford173@gmail.com>
Cc:     linux-media@vger.kernel.org, mchehab@kernel.org,
        linux-kernel@vger.kernel.org
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Precedence: bulk

Hi Adam

Sorry for the delay in reviewing.

On Sat, 9 Jul 2022 at 14:51, Adam Ford <aford173@gmail.com> wrote:
>
> The imx219 camera is capable of either two-lane or four-lane
> operation.  When operating in four-lane, both the pixel rate and
> link frequency change. Regardless of the mode, however, both
> frequencies remain fixed.
>
> Helper functions are needed to read and set pixel and link frequencies
> which also reduces the number of fixed registers in the table of modes.
>
> Since the link frequency and number of lanes is extracted from the
> endpoint, move the endpoint handling into the probe function and
> out of the imx219_check_hwcfg.  This simplifies the imx219_check_hwcfg
> just a bit.

This paragraph isn't relevant any more.

> Signed-off-by: Adam Ford <aford173@gmail.com>
> ---
> V3:  Keep the helper function doing the link and lane parsing to
>      keep th probe function small.
>
> diff --git a/drivers/media/i2c/imx219.c b/drivers/media/i2c/imx219.c
> index faa5dab3c2ec..bb4125e7e113 100644
> --- a/drivers/media/i2c/imx219.c
> +++ b/drivers/media/i2c/imx219.c
> @@ -42,10 +42,16 @@
>  /* External clock frequency is 24.0M */
>  #define IMX219_XCLK_FREQ               24000000
>
> -/* Pixel rate is fixed at 182.4M for all the modes */
> +/* Pixel rate is fixed for all the modes */
>  #define IMX219_PIXEL_RATE              182400000
> +#define IMX219_PIXEL_RATE_4LANE                280800000
>
>  #define IMX219_DEFAULT_LINK_FREQ       456000000
> +#define IMX219_DEFAULT_LINK_FREQ_4LANE 363000000
> +
> +#define IMX219_REG_CSI_LANE_MODE       0x0114
> +#define IMX219_CSI_2_LANE_MODE         0x01
> +#define IMX219_CSI_4_LANE_MODE         0x03
>
>  /* V_TIMING internal */
>  #define IMX219_REG_VTS                 0x0160
> @@ -299,6 +305,10 @@ static const s64 imx219_link_freq_menu[] = {
>         IMX219_DEFAULT_LINK_FREQ,
>  };
>
> +static const s64 imx219_link_freq_4lane_menu[] = {
> +       IMX219_DEFAULT_LINK_FREQ_4LANE,
> +};
> +
>  static const char * const imx219_test_pattern_menu[] = {
>         "Disabled",
>         "Color Bars",
> @@ -474,6 +484,9 @@ struct imx219 {
>
>         /* Streaming on/off */
>         bool streaming;
> +
> +       /* Two or Four lanes */
> +       u8 lanes;
>  };
>
>  static inline struct imx219 *to_imx219(struct v4l2_subdev *_sd)
> @@ -936,6 +949,13 @@ static int imx219_get_selection(struct v4l2_subdev *sd,
>         return -EINVAL;
>  }
>
> +static int imx219_configure_lanes(struct imx219 *imx219)
> +{
> +       return imx219_write_reg(imx219, IMX219_REG_CSI_LANE_MODE,
> +                               IMX219_REG_VALUE_08BIT, (imx219->lanes == 2) ?
> +                               IMX219_CSI_2_LANE_MODE : IMX219_CSI_4_LANE_MODE);
> +};
> +
>  static int imx219_start_streaming(struct imx219 *imx219)
>  {
>         struct i2c_client *client = v4l2_get_subdevdata(&imx219->sd);
> @@ -953,6 +973,13 @@ static int imx219_start_streaming(struct imx219 *imx219)
>                 goto err_rpm_put;
>         }
>
> +       /* Configure two or four Lane mode */
> +       ret = imx219_configure_lanes(imx219);
> +       if (ret) {
> +               dev_err(&client->dev, "%s failed to configure lanes\n", __func__);
> +               goto err_rpm_put;
> +       }
> +
>         /* Apply default values of current mode */
>         reg_list = &imx219->mode->reg_list;
>         ret = imx219_write_regs(imx219, reg_list->regs, reg_list->num_of_regs);
> @@ -1184,6 +1211,11 @@ static const struct v4l2_subdev_internal_ops imx219_internal_ops = {
>         .open = imx219_open,
>  };
>
> +static unsigned long imx219_get_pixel_rate(struct imx219 *imx219)
> +{
> +       return (imx219->lanes == 2) ? IMX219_PIXEL_RATE : IMX219_PIXEL_RATE_4LANE;
> +}
> +
>  /* Initialize control handlers */
>  static int imx219_init_controls(struct imx219 *imx219)
>  {
> @@ -1205,15 +1237,16 @@ static int imx219_init_controls(struct imx219 *imx219)
>         /* By default, PIXEL_RATE is read only */
>         imx219->pixel_rate = v4l2_ctrl_new_std(ctrl_hdlr, &imx219_ctrl_ops,
>                                                V4L2_CID_PIXEL_RATE,
> -                                              IMX219_PIXEL_RATE,
> -                                              IMX219_PIXEL_RATE, 1,
> -                                              IMX219_PIXEL_RATE);
> +                                              imx219_get_pixel_rate(imx219),
> +                                              imx219_get_pixel_rate(imx219), 1,
> +                                              imx219_get_pixel_rate(imx219));
>
>         imx219->link_freq =
>                 v4l2_ctrl_new_int_menu(ctrl_hdlr, &imx219_ctrl_ops,
>                                        V4L2_CID_LINK_FREQ,
>                                        ARRAY_SIZE(imx219_link_freq_menu) - 1, 0,
> -                                      imx219_link_freq_menu);
> +                                      (imx219->lanes == 2) ? imx219_link_freq_menu :
> +                                      imx219_link_freq_4lane_menu);
>         if (imx219->link_freq)
>                 imx219->link_freq->flags |= V4L2_CTRL_FLAG_READ_ONLY;
>
> @@ -1308,7 +1341,7 @@ static void imx219_free_controls(struct imx219 *imx219)
>         mutex_destroy(&imx219->mutex);
>  }
>
> -static int imx219_check_hwcfg(struct device *dev)
> +static int imx219_check_hwcfg(struct device *dev, struct imx219 *imx219)
>  {
>         struct fwnode_handle *endpoint;
>         struct v4l2_fwnode_endpoint ep_cfg = {
> @@ -1328,10 +1361,12 @@ static int imx219_check_hwcfg(struct device *dev)
>         }
>
>         /* Check the number of MIPI CSI2 data lanes */
> -       if (ep_cfg.bus.mipi_csi2.num_data_lanes != 2) {
> -               dev_err(dev, "only 2 data lanes are currently supported\n");
> +       if (ep_cfg.bus.mipi_csi2.num_data_lanes != 2 &&
> +           ep_cfg.bus.mipi_csi2.num_data_lanes != 4) {
> +               dev_err(dev, "only 2 or 4 data lanes are currently supported\n");
>                 goto error_out;
>         }
> +       imx219->lanes = ep_cfg.bus.mipi_csi2.num_data_lanes;
>
>         /* Check the link frequency set in device tree */
>         if (!ep_cfg.nr_of_link_frequencies) {
> @@ -1339,8 +1374,8 @@ static int imx219_check_hwcfg(struct device *dev)
>                 goto error_out;
>         }
>
> -       if (ep_cfg.nr_of_link_frequencies != 1 ||
> -           ep_cfg.link_frequencies[0] != IMX219_DEFAULT_LINK_FREQ) {
> +       if (ep_cfg.link_frequencies[0] != ((imx219->lanes == 2) ?
> +           IMX219_DEFAULT_LINK_FREQ : IMX219_DEFAULT_LINK_FREQ_4LANE)) {

You've lost the check of ep_cfg.nr_of_link_frequencies != 1 in this update.

Otherwise it looks good to me.

  Dave

>                 dev_err(dev, "Link frequency not supported: %lld\n",
>                         ep_cfg.link_frequencies[0]);
>                 goto error_out;
> @@ -1368,7 +1403,7 @@ static int imx219_probe(struct i2c_client *client)
>         v4l2_i2c_subdev_init(&imx219->sd, client, &imx219_subdev_ops);
>
>         /* Check the hardware configuration in device tree */
> -       if (imx219_check_hwcfg(dev))
> +       if (imx219_check_hwcfg(dev, imx219))
>                 return -EINVAL;
>
>         /* Get system clock (xclk) */
> --
> 2.34.1
>