linux-kernel - Re: [PATCH v3 6/6] drm/ingenic: Attach bridge chain to encoders

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Date:   Mon, 27 Sep 2021 18:18:25 +0200
From:   "H. Nikolaus Schaller" <hns@...delico.com>
To:     Paul Cercueil <paul@...pouillou.net>
Cc:     Paul Boddie <paul@...die.org.uk>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        linux-mips <linux-mips@...r.kernel.org>, list@...ndingux.net,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 6/6] drm/ingenic: Attach bridge chain to encoders

Hi Paul,

> Am 25.09.2021 um 21:39 schrieb Paul Cercueil <paul@...pouillou.net>:
> 
> 
> 
> Le sam., sept. 25 2021 at 21:26:42 +0200, H. Nikolaus Schaller <hns@...delico.com> a écrit :
>> Hi Paul,
>>> Am 25.09.2021 um 21:08 schrieb Paul Cercueil <paul@...pouillou.net>:
>>> Hi Paul & Nikolaus,
>>> If you spent some time debugging the issue
>> we did ...
> 
> By saying that you didn't debug,

We did - but sometimes you don't see the wood for the trees.

> (null) means you're printing a NULL pointer. So I could see that hdmi->next_bridge was NULL.

I remember we did find this, but did not understand that it should be initialized by dw-hdmi.
And because we though that dw-hdmi has it its own connector, it is ok that way.

> The place that sets it is dw_hdmi_parse_dt, which will return early with code 0, before next_bridge is set, if plat_data->output_port == 0, which was your case.

Well, we were still at 5.14 when we did these initial attempts to use hdmi-connector with synopsys.
Back then, there was no dw_hdmi_parse_dt and no output_port.

IAW: we did not even have a chance to make it work on top of 5.14 the hdmi-connector way. And were sucessful.

I just noticed this when trying to backport the last puzzle piece...

Well, it is always difficult to hit a moving target.

> Since your hdmi-connector is wired at port #1, then .output_port should be 1 as well.

Anyways it works now for 5.14.8 (our internal test) and 5.15-rc3.

And v4 of the jz4780 hdmi stuff will follow.

BR and thanks,
Nikolaus