Hi Sam, Em Wed, 19 Aug 2020 19:35:58 +0200 Sam Ravnborg <sam@xxxxxxxxxxxx> escreveu: > > + ret = drm_bridge_attach(encoder, bridge, NULL, 0); > The bridge should be attached with the falg that tell the bridge NOT to > create a connector. > > The display driver shall created the connector. > > Please see how other drivers do this (but most driver uses the old > pattern so so look for drm_bridge_attach() with the flag argument. Not sure if I got what should be done here. >From what I've seen at the DRM code, one of the differences between the display engine for the first Hikey board (Kirin 620 based) and 960/970 is with regards to bridges. The first Hikey device doesn't use any external bridges: both panel and HDMI support are provided by the SoC. The Hikey 960 and 970 boards may either use an external bridge or not. They also have two output connectors: - The first one doesn't use an external bridge. It is used only together with an external daughter display panel board. It sounds that one such panels is this one: https://www.96boards.org/blog/linksprite-hikey-aosp/ I don't have any such board. The OOT driver came with one panel display, I didn't port such driver. - The second one uses an external bridge (adv7535) which is connected to the HDMI board's connector. As there's just one bridge, the driver uses this to find its OF data: struct device_node *bridge_node; bridge_node = of_graph_get_remote_port_parent(endpoint); dsi->bridge = of_drm_find_bridge(bridge_node); Basically, it doesn't call drm_bridge_add(), and doesn't declare any struct drm_bridge_funcs fops, as there's just one bridge that it is always there. - That's said, when I ported the code from Kernel 4.9, I fixed some broken things at the hotplug logic, trying to use other drivers with external bridges as examples. Yet, as you noticed, I ended using some older bridge model. The only other driver I found that doesn't use drm_bridge_add() and doesn't pass 0 as flags is this one: drivers/gpu/drm/omapdrm/omap_drv.c Is it a good example? What I see different there there is that it calls drm_bridge_attach() with: ret = drm_bridge_attach(pipe->encoder, pipe->output->bridge, NULL, DRM_BRIDGE_ATTACH_NO_CONNECTOR); Is adding this enough? Or should I do something else? Thanks, Mauro
