On Tue, Mar 08, 2022 at 03:47:22PM +0100, Marek Vasut wrote:
On 3/8/22 14:49, Maxime Ripard wrote:
On Tue, Mar 08, 2022 at 02:27:40PM +0100, Marek Vasut wrote:
On 3/8/22 13:51, Maxime Ripard wrote:
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. > > > > [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@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).
That's out of scope of this series anyway, so Jagan can implement patches for that mode if needed.
Not really? You can't count on the port@0 being there generally speaking, so you can't count on data-lanes being there either, which exactly what you're doing in this patch.
I can because the upstream DT bindings currently say port@0 must be present, see above. If that requirement should be relaxed, sure, but that's a separate series.
And another upstream DT bindings say that you don't need them at all. Yes, there's a conflict. Yes, it's unfortunate. But the generic DSI binding is far more relevant than a single bridge driver.
So figuring it out is very much a prerequisite to that series, especially since those patches effectively make the OF-graph mandatory in some situations, while it was purely aesthetics before.
Maxime