On 25/08/2022 14:48, Linus Walleij wrote:
On Wed, Aug 17, 2022 at 3:31 PM Neil Armstrong <narmstr...@baylibre.com> wrote:
On 15/08/2022 02:15, Dmitry Osipenko wrote:
08.08.2022 12:51, Neil Armstrong пишет:
On 08/08/2022 11:15, Neil Armstrong wrote:
This patch broke ARM/QEMU vexpress display because of_drm_find_bridge()
always fail with -EPROBE_DEFER. Reverting this patch returns display
back. Please fix or revert, thanks in advance.
Can you share a QEMU cmdline to reproduce ?
Actually the vexpress DT has multiple input ports instead of a single
input port at @0
and an output port at @1 like documented in the bindings:
vexpress-v2m.dtsi#L303-L307:
ports {
#address-cells = <1>;
#size-cells = <0>;
/*
* Both the core tile and the motherboard routes their output
* pads to this transmitter. The motherboard system controller
* can select one of them as input using a mux register in
* "arm,vexpress-muxfpga". The Vexpress with the CA9 core tile is
* the only platform with this specific set-up.
*/
port@0 {
reg = <0>;
dvi_bridge_in_ct: endpoint {
remote-endpoint = <&clcd_pads_ct>;
};
};
port@1 {
reg = <1>;
dvi_bridge_in_mb: endpoint {
remote-endpoint = <&clcd_pads_mb>;
};
};
};
bindings:
ports:
$ref: /schemas/graph.yaml#/properties/ports
properties:
port@0:
$ref: /schemas/graph.yaml#/properties/port
description: Parallel RGB input port
port@1:
$ref: /schemas/graph.yaml#/properties/port
description: HDMI output port
port@3:
$ref: /schemas/graph.yaml#/properties/port
description: Sound input port
The patch is conform to the bindings, the DT was working but is actually
not valid.
I haven't looked closely at how to fix this properly, but if we can fix
it using of_machine_is_compatible("arm,vexpress") workaround in the
driver, then it will be good enough at least as a temporal fix, IMO.
If other maintainers are ok with that, it can be temporary fix until the DT
gets fixed.
That's fine with me, will you send a patch?
Who, me ?
I don't know how you expect the DT to get "fixed" though.
The hardware looks like this, it's maybe not the most elegant
electronics design but it exists, so... I wrote this DT with two
inputs, see commit f1fe12c8bf332, the code handling this
awkward mux is part of the DRM driver, see
drivers/gpu/drm/pl111/pl111_versatile.c function
pl111_vexpress_clcd_init() for an idea of how it works.
The proper fix would be the other way around, adding a mux bridge before the
sii902x
returning the next bridge or nothing to the right controller.
Yours,
Linus Walleij
Neil
