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

[Jagan Teki]

On Tue, Mar 8, 2022 at 3:19 PM Marek Vasut <marex at denx.de> wrote:
>
> On 3/8/22 09:03, Jagan Teki wrote:
>
> Hi,
>
> [...]
>
> >> @@ -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/
>
> The link points to a patch marked "DO NOT MERGE", maybe that patch is
> missing the DSI host port at 0 OF graph link ? Both port at 0 and port at 1 are
> required, see:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/display/bridge/chipone,icn6211.yaml#n53
>
> What is "non-ports-based OF graph" ?
>
> I don't see drm_of_find_bridge() in linux-next , what is that ?

port at 0 is optional as some of the DSI host OF-graph represent the
bridge or panel as child nodes instead of ports. (i think dt-binding
has to fix it to make port at 0 optional)

Example OF-graph is on the commit message.
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/drivers/gpu/drm/drm_of.c?id=80253168dbfd256bca97cf7f13312863c5a7f2e5

Jagan.