Re: [PATCH V3 05/13] drm: bridge: icn6211: Add DSI lane count DT property parsing

[Jagan Teki <jagan@amarulasolutions.com>]

Hi Marek,

On Fri, Mar 4, 2022 at 5:55 AM Marek Vasut <marex@denx.de> wrote:
>
> The driver currently hard-codes DSI lane count to two, however the chip
> is capable of operating in 1..4 DSI lanes mode. Parse 'data-lanes' DT
> property and program the result into DSI_CTRL register.
>
> Signed-off-by: Marek Vasut <marex@denx.de>
> Cc: Jagan Teki <jagan@amarulasolutions.com>
> Cc: Maxime Ripard <maxime@cerno.tech>
> Cc: Robert Foss <robert.foss@linaro.org>
> Cc: Sam Ravnborg <sam@ravnborg.org>
> Cc: Thomas Zimmermann <tzimmermann@suse.de>
> To: dri-devel@lists.freedesktop.org
> ---
> V2: Rebase on next-20220214
> V3: Default to 4 data lanes unless specified otherwise
> ---
>  drivers/gpu/drm/bridge/chipone-icn6211.c | 45 +++++++++++++++++++++---
>  1 file changed, 41 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/chipone-icn6211.c b/drivers/gpu/drm/bridge/chipone-icn6211.c
> index 2ac8eb7e25f52..df8e75a068ad0 100644
> --- a/drivers/gpu/drm/bridge/chipone-icn6211.c
> +++ b/drivers/gpu/drm/bridge/chipone-icn6211.c
> @@ -136,10 +136,12 @@ struct chipone {
>         struct drm_bridge bridge;
>         struct drm_display_mode mode;
>         struct drm_bridge *panel_bridge;
> +       struct device_node *host_node;
>         struct gpio_desc *enable_gpio;
>         struct regulator *vdd1;
>         struct regulator *vdd2;
>         struct regulator *vdd3;
> +       int dsi_lanes;
>  };
>
>  static inline struct chipone *bridge_to_chipone(struct drm_bridge *bridge)
> @@ -212,6 +214,11 @@ static void chipone_atomic_enable(struct drm_bridge *bridge,
>         /* dsi specific sequence */
>         ICN6211_DSI(icn, SYNC_EVENT_DLY, 0x80);
>         ICN6211_DSI(icn, HFP_MIN, hfp & 0xff);
> +
> +       /* DSI data lane count */
> +       ICN6211_DSI(icn, DSI_CTRL,
> +                   DSI_CTRL_UNKNOWN | DSI_CTRL_DSI_LANES(icn->dsi_lanes - 1));
> +
>         ICN6211_DSI(icn, MIPI_PD_CK_LANE, 0xa0);
>         ICN6211_DSI(icn, PLL_CTRL(12), 0xff);
>
> @@ -314,7 +321,9 @@ static const struct drm_bridge_funcs chipone_bridge_funcs = {
>  static int chipone_parse_dt(struct chipone *icn)
>  {
>         struct device *dev = icn->dev;
> +       struct device_node *endpoint;
>         struct drm_panel *panel;
> +       int dsi_lanes;
>         int ret;
>
>         icn->vdd1 = devm_regulator_get_optional(dev, "vdd1");
> @@ -350,15 +359,42 @@ static int chipone_parse_dt(struct chipone *icn)
>                 return PTR_ERR(icn->enable_gpio);
>         }
>
> +       endpoint = of_graph_get_endpoint_by_regs(dev->of_node, 0, 0);
> +       dsi_lanes = of_property_count_u32_elems(endpoint, "data-lanes");
> +       icn->host_node = of_graph_get_remote_port_parent(endpoint);
> +       of_node_put(endpoint);
> +
> +       if (!icn->host_node)
> +               return -ENODEV;

The non-ports-based OF graph returns a -19 example on the Allwinner
Display pipeline in R16 [1].

We need to have a helper to return host_node for non-ports as I have
done it for drm_of_find_bridge.

[1] https://patchwork.amarulasolutions.com/patch/1805/

Thanks,
Jagan.