[PATCH v7 2/2] drm/bridge: add it6505 driver to read data-lanes and link-frequencies from dt

[Pin-yen Lin]

Hi all,
Friendly ping on this patch.

Regards,
Pin-yen

On Thu, Nov 3, 2022 at 5:13 PM allen <allen.chen at ite.com.tw> wrote:
>
> From: allen chen <allen.chen at ite.com.tw>
>
> Add driver to read data-lanes and link-frequencies from dt property to
> restrict output bandwidth.
>
> Signed-off-by: Allen chen <allen.chen at ite.com.tw>
> Signed-off-by: Pin-yen Lin <treapking at chromium.org>
> ---
>  drivers/gpu/drm/bridge/ite-it6505.c | 80 +++++++++++++++++++++++++++--
>  1 file changed, 77 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
> index a4302492cf8df..ed4536cde3140 100644
> --- a/drivers/gpu/drm/bridge/ite-it6505.c
> +++ b/drivers/gpu/drm/bridge/ite-it6505.c
> @@ -437,6 +437,8 @@ struct it6505 {
>         bool powered;
>         bool hpd_state;
>         u32 afe_setting;
> +       u32 max_dpi_pixel_clock;
> +       u32 max_lane_count;
>         enum hdcp_state hdcp_status;
>         struct delayed_work hdcp_work;
>         struct work_struct hdcp_wait_ksv_list;
> @@ -1476,7 +1478,8 @@ static void it6505_parse_link_capabilities(struct it6505 *it6505)
>         it6505->lane_count = link->num_lanes;
>         DRM_DEV_DEBUG_DRIVER(dev, "Sink support %d lanes training",
>                              it6505->lane_count);
> -       it6505->lane_count = min_t(int, it6505->lane_count, MAX_LANE_COUNT);
> +       it6505->lane_count = min_t(int, it6505->lane_count,
> +                                  it6505->max_lane_count);
>
>         it6505->branch_device = drm_dp_is_branch(it6505->dpcd);
>         DRM_DEV_DEBUG_DRIVER(dev, "Sink %sbranch device",
> @@ -2912,7 +2915,7 @@ it6505_bridge_mode_valid(struct drm_bridge *bridge,
>         if (mode->flags & DRM_MODE_FLAG_INTERLACE)
>                 return MODE_NO_INTERLACE;
>
> -       if (mode->clock > DPI_PIXEL_CLK_MAX)
> +       if (mode->clock > it6505->max_dpi_pixel_clock)
>                 return MODE_CLOCK_HIGH;
>
>         it6505->video_info.clock = mode->clock;
> @@ -3099,10 +3102,32 @@ static int it6505_init_pdata(struct it6505 *it6505)
>         return 0;
>  }
>
> +static int it6505_get_data_lanes_count(const struct device_node *endpoint,
> +                                      const unsigned int min,
> +                                      const unsigned int max)
> +{
> +       int ret;
> +
> +       ret = of_property_count_u32_elems(endpoint, "data-lanes");
> +       if (ret < 0)
> +               return ret;
> +
> +       if (ret < min || ret > max)
> +               return -EINVAL;
> +
> +       return ret;
> +}
> +
>  static void it6505_parse_dt(struct it6505 *it6505)
>  {
>         struct device *dev = &it6505->client->dev;
> +       struct device_node *np = dev->of_node, *ep = NULL;
> +       int len;
> +       u64 link_frequencies;
> +       u32 data_lanes[4];
>         u32 *afe_setting = &it6505->afe_setting;
> +       u32 *max_lane_count = &it6505->max_lane_count;
> +       u32 *max_dpi_pixel_clock = &it6505->max_dpi_pixel_clock;
>
>         it6505->lane_swap_disabled =
>                 device_property_read_bool(dev, "no-laneswap");
> @@ -3118,7 +3143,56 @@ static void it6505_parse_dt(struct it6505 *it6505)
>         } else {
>                 *afe_setting = 0;
>         }
> -       DRM_DEV_DEBUG_DRIVER(dev, "using afe_setting: %d", *afe_setting);
> +
> +       ep = of_graph_get_endpoint_by_regs(np, 1, 0);
> +       of_node_put(ep);
> +
> +       if (ep) {
> +               len = it6505_get_data_lanes_count(ep, 1, 4);
> +
> +               if (len > 0 && len != 3) {
> +                       of_property_read_u32_array(ep, "data-lanes",
> +                                                  data_lanes, len);
> +                       *max_lane_count = len;
> +               } else {
> +                       *max_lane_count = MAX_LANE_COUNT;
> +                       dev_err(dev, "error data-lanes, use default");
> +               }
> +       } else {
> +               *max_lane_count = MAX_LANE_COUNT;
> +               dev_err(dev, "error endpoint, use default");
> +       }
> +
> +       ep = of_graph_get_endpoint_by_regs(np, 0, 0);
> +       of_node_put(ep);
> +
> +       if (ep) {
> +               len = of_property_read_variable_u64_array(ep,
> +                                                         "link-frequencies",
> +                                                         &link_frequencies, 0,
> +                                                         1);
> +               if (len >= 0) {
> +                       do_div(link_frequencies, 1000);
> +                       if (link_frequencies > 297000) {
> +                               dev_err(dev,
> +                                       "max pixel clock error, use default");
> +                               *max_dpi_pixel_clock = DPI_PIXEL_CLK_MAX;
> +                       } else {
> +                               *max_dpi_pixel_clock = link_frequencies;
> +                       }
> +               } else {
> +                       dev_err(dev, "error link frequencies, use default");
> +                       *max_dpi_pixel_clock = DPI_PIXEL_CLK_MAX;
> +               }
> +       } else {
> +               dev_err(dev, "error endpoint, use default");
> +               *max_dpi_pixel_clock = DPI_PIXEL_CLK_MAX;
> +       }
> +
> +       DRM_DEV_DEBUG_DRIVER(dev, "using afe_setting: %u, max_lane_count: %u",
> +                            it6505->afe_setting, it6505->max_lane_count);
> +       DRM_DEV_DEBUG_DRIVER(dev, "using max_dpi_pixel_clock: %u kHz",
> +                            it6505->max_dpi_pixel_clock);
>  }
>
>  static ssize_t receive_timing_debugfs_show(struct file *file, char __user *buf,
> --
> 2.25.1
>