linux-kernel - Q: What ist the standard way to define connector type and bus format with device tree?

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Date:   Sun, 28 Feb 2021 22:10:23 +0100
From:   "H. Nikolaus Schaller" <hns@...delico.com>
To:     Sam Ravnborg <sam@...nborg.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     Paul Boddie <paul@...die.org.uk>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        ML dri-devel <dri-devel@...ts.freedesktop.org>,
        Discussions about the Letux Kernel 
        <letux-kernel@...nphoenux.org>
Subject: Q: What ist the standard way to define connector type and bus format with device tree?

No expert available?

Let me refine the question:

By using the descriptions of panel-common.yaml and panel-timing.yaml it
is possible to define a simple-panel by pure DTS means.

This timing setup is done by code through:

git blame drivers/gpu/drm/panel/panel-simple.c | grep of_get_display_timing
4a1d0dbc8332231 (Sam Ravnborg            2020-02-16 19:15:13 +0100  431) 	ret = of_get_display_timing(np, "panel-timing", timing);
4a1d0dbc8332231 (Sam Ravnborg            2020-02-16 19:15:13 +0100  566) 		if (!of_get_display_timing(dev->of_node, "panel-timing", &dt))

But it seems to lack a mechanism to define the connector type and bus format
which is needed to make a panel finally work.

Are we missing something or is the code/property missing?

If it is the first, please let us know so that we can use it.
If code is missing, please let us know so that we can suggest a patch.

BR and thanks,
Nikolaus


> Am 31.01.2021 um 11:54 schrieb H. Nikolaus Schaller <hns@...delico.com>:
> 
> ping?
> 
>> Am 12.01.2021 um 12:41 schrieb H. Nikolaus Schaller <hns@...delico.com>:
>> 
>> Hi,
>> according to bindings/display/panel/panel-common.yaml
>> and by using "panel-simple" as compatible string we
>> can define almost all properties of a DSI panel by a
>> device tree entry.
>> 
>> Except the connector type and bus format which can only be
>> set by adding the information to the panel-simple tables.
>> 
>> This leads to big problems because DRM can't match the
>> display with any lcd controller. A smaller issue is a
>> warning:
>> 
>> [    0.313431] panel-simple claa070vc01: Specify missing connector_type
>> 
>> Are we missing some documentation or code that reads
>> some "connector-type" and "bus-format" property?
>> 
>> BR and thanks,
>> Nikolaus
>