Hi Sam,
Em Wed, 19 Aug 2020 19:35:58 +0200
Sam Ravnborg <[email protected]> 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
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