Hi Archit,
I'm a relative n00b here, but I'm trying to follow along and I have some questions:
On Fri, Dec 01, 2017 at 06:29:04PM +0530, Archit Taneja wrote:
On 11/30/2017 11:02 PM, Nickey Yang wrote:
I try to follow as you suggested,use
mipi_dsi: mipi@ff960000 { ... ... clock-master; /* implies that this DSI instance drivers the clock * for both the DSIs. */ ports { mipi_in: port { ... ... }; /* add extra output ports for both DSIs */ mipi_out: port { mipi_panel_out: endpoint { remote-endpoint = <&panel_in_channel0>; }; }; }; panel { ... ... /* * panel node can describe its input ports, if both the DSIs output * ports are connected to the same device (i.e, the same DSI panel), * we can assume that the DSIs need to operate in dual DSI mode */ ports { ... port@0 { panel_in_channel0: endpoint { remote-endpoint = <&mipi_panel_out>; }; }; port@1 { panel_in_channel1: endpoint { remote-endpoint = <&mipi1_panel_out>; };
}; }; }; };
mipi_dsi1: mipi@ff968000 { ... ... ports { mipi1_in: port { ... ... }; mipi1_out: port { mipi1_panel_out: endpoint { remote-endpoint = <&panel_in_channel1>; }; }; }; }
But it seems we can not use of_drm_find_panel(like below)
/* port = of_graph_get_port_by_id(dev->of_node, 1); if (port) { endpoint = of_get_child_by_name(port, "endpoint"); of_node_put(port); if (!endpoint) { dev_err(dev, "no output endpoint found\n"); return -EINVAL; } panel_node = of_graph_get_remote_port_parent(endpoint); of_node_put(endpoint); if (!panel_node) { dev_err(dev, "no output node found\n"); return -EINVAL; } panel = of_drm_find_panel(panel_node); of_node_put(panel_node); if (!panel) return -EPROBE_DEFER; } */ to get DSI1 outputs,because of_drm_find_panel need compare
if (panel->dev->of_node == np)
in dsi_panel driver innolux->base.dev = &innolux->link->dev; dsi->dev
Yes, we should only have 1 drm_panel in the global panel list. Shouldn't it be possible to modify the dsi driver such that dsi1 doesn't care whether it has a drm_panel for it or not, if we are in dual dsi mode?
I imagine a sequence like this:
- dsi0 probes, parses the of-graph, finds the panel and saves its device
node.
Does this mean we depend on probe order? Or would we be able to -EPROBE_DEFER or similar if dsi1 binds first?
- dsi1 probes, parses the of-graph, find the panel's device node
- dsi1 checks if it is the same as the panel attached to dsi0.
- If so, it just takes the drm_panel pointer from dsi0.
- If not, it tries a of_drm_find_panel() on the panel's device node.
So, that all means we'd need a new variant of drm_of_find_panel_or_bridge() for "dual" drivers like this? Or else open-code this logic in dw-mipi-dsi.c?
A dual DSI panel driver would also be a bit different. It will be a mipi_dsi_driver with the master DSI (dsi0) as the mipi_dsi_device. Using the of-graph helpers, we would get the device node of dsi1 using of_find_mipi_dsi_host_by_node(), and create another DSI device using mipi_dsi_device_register_full(). Then, we call mipi_dsi_attach() on both the dsi devices.
That seems...interesting. I guess that sounds like it could work, but someone would have to play with that a bit more.
I assume one wouldn't want to do all this in every dual DSI driver that needs this, right?
struct innolux_panel { struct drm_panel base; struct mipi_dsi_device *link; }; It means one panel can only be found in his dsi node,(like dsi0 above).
I'm doubting about it, Or may we follow tegra_dsi_ganged_probe (drivers/gpu/drm/tergra/dsi.c) method.
This method will add a new binding similar to "nvidia,ganged-mode", which is something we don't want to do.
It's unfortunate we have the anti-pattern already merged :(
Brian