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Subject: Re: [PATCH v3 6/6] drm/ingenic: Attach bridge chain to encoders
From:   "H. Nikolaus Schaller" <hns@goldelico.com>
In-Reply-To: <B7B431EC-BC73-4B39-A03C-003347D8C239@goldelico.com>
Date:   Fri, 24 Sep 2021 13:40:16 +0200
Cc:     Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        linux-mips <linux-mips@vger.kernel.org>, list@opendingux.net,
        dri-devel <dri-devel@lists.freedesktop.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Paul Boddie <paul@boddie.org.uk>
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To:     Paul Cercueil <paul@crapouillou.net>
Precedence: bulk

Hi Paul,

> Am 23.09.2021 um 22:23 schrieb H. Nikolaus Schaller =
<hns@goldelico.com>:
>=20
>=20
>> Because your "it doesn't work" arguments have zero weight otherwise.
>=20
> I hope I still can find it. So I can't promise anything.
> We have had it complete in DTS and added code to parse it.
> It may have been wiped out by cleaning up patch series during rebase.

I was able to locate it and place it on top of your ingenic-drm-drv v3
and our synopsys hdmi v3 [1] (+ unpublished work).

This [2] should save you a lot of time making dw-hdmi work on jz4780 at =
all, so you can
focus on our mistakes instead of starting from scratch.

Features:
- based on v5.15-rc2
- (the first two patches are LetuxOS and build system related and can be =
ignored for this discussion)
- contains some significant patch from drm-next not yet upstream
- contains your v3 series as is
- (initially) disables your DRM_BRIDGE_ATTACH_NO_CONNECTOR (is reverted =
in the last patch)
- adds synopsys stuff and DT schema
- adds jz4780.dtsi and ci20.dts
- adds ci20_defconfig
- (adds some (optional) jz4780 specific features we likely do not need =
now)
- adds something to dw-hdmi to properly notify HPD
- adds a hdmi-regulator so that HPD power can be turned on/off
- (attempt to configure the dw-hdmi unwedge feature)
- then we add the hdmi-connector to replace the dw-hdmi connector to =
device tree
- and finally re-enable DRM_BRIDGE_ATTACH_NO_CONNECTOR

The result is
a) without the last patch I get a proper setup with framebuffer and =
edid.
Unfortunateley without any image on HDMI.

b) if last patch is included
(so that DRM_BRIDGE_ATTACH_NO_CONNECTOR is required as by your [patch v3 =
6/6] again)
I get:

[    4.351200] [drm:drm_bridge_attach [drm]] *ERROR* failed to attach =
bridge /hdmi@10180000 to encoder DPI-34: -22
[    4.474346] [drm:drm_bridge_attach [drm]] *ERROR* failed to attach =
bridge (null) to encoder DPI-34: -22
[    4.562125] ingenic-drm 13050000.lcdc0: Unable to attach bridge
[    4.568103] ingenic-drm: probe of 13050000.lcdc0 failed with error =
-22

Maybe you can spot the bug in the code much quicker than we can.

I do not know what Paul Boddie did differently if this initialization
with connector-hdmi works for him and does not fail likewise.

BR and thanks,
Nikolaus


[1]: =
https://lore.kernel.org/linux-mips/8e873f17fcc9aeb326d99b7c2c8cd25b61dca6f=
5.1628399442.git.hns@goldelico.com/T/
[2]: =
https://git.goldelico.com/?p=3Dletux-kernel.git;a=3Dshortlog;h=3Drefs/head=
s/upstream%2Bjz4780%2Bhdmi-connector