On Tue, Mar 08, 2022 at 11:29:59AM +0100, Marek Vasut wrote:
On 3/8/22 11:07, Jagan Teki wrote:
On Tue, Mar 8, 2022 at 3:19 PM Marek Vasut marex@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.
The link points to a patch marked "DO NOT MERGE", maybe that patch is missing the DSI host port@0 OF graph link ? Both port@0 and port@1 are required, see:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Docu...
What is "non-ports-based OF graph" ?
I don't see drm_of_find_bridge() in linux-next , what is that ?
port@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@0 optional)
The current upstream DT binding document says:
required: - port@0 - port@1So port@0 is mandatory.
In the binding, sure, but fundamentally the DT excerpt Jagan provided is correct. If the bridge supports DCS, there's no reason to use the OF graph in the first place: the bridge node will be a child node of the MIPI-DSI controller (and there's no obligation to use the OF-graph for a MIPI-DSI controller).
I believe port@0 should be made optional (or downright removed if MIPI-DCS in the only control bus).
Maxime