linux-kernel - Re: [PATCH v12 2/9] drm/ingenic: Add support for JZ4780 and HDMI output

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Date:   Wed, 2 Feb 2022 13:33:15 +0100
From:   "H. Nikolaus Schaller" <hns@...delico.com>
To:     Paul Cercueil <paul@...pouillou.net>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Kees Cook <keescook@...omium.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Neil Armstrong <narmstrong@...libre.com>,
        Robert Foss <robert.foss@...aro.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Harry Wentland <harry.wentland@....com>,
        Sam Ravnborg <sam@...nborg.org>,
        Maxime Ripard <maxime@...no.tech>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Paul Boddie <paul@...die.org.uk>,
        Andrzej Hajda <andrzej.hajda@...el.com>,
        Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
        devicetree@...r.kernel.org, linux-mips@...r.kernel.org,
        linux-kernel@...r.kernel.org, letux-kernel@...nphoenux.org,
        Jonas Karlman <jonas@...boo.se>,
        dri-devel@...ts.freedesktop.org,
        Ezequiel Garcia <ezequiel@...labora.com>
Subject: Re: [PATCH v12 2/9] drm/ingenic: Add support for JZ4780 and HDMI
 output



> Am 02.02.2022 um 13:28 schrieb Paul Cercueil <paul@...pouillou.net>:
> 
> 
> 
> Le mer., févr. 2 2022 at 13:17:14 +0100, H. Nikolaus Schaller <hns@...delico.com> a écrit :
>> Hi Paul,
>>> Am 02.02.2022 um 13:06 schrieb Paul Cercueil <paul@...pouillou.net>:
>>> Hi Nikolaus,
>>>>>> @@ -446,6 +454,9 @@ static int ingenic_drm_plane_atomic_check(struct drm_plane *plane,
>>>>>> 	if (!crtc)
>>>>>> 		return 0;
>>>>>> +	if (plane == &priv->f0)
>>>>>> +		return -EINVAL;
>>>>> This will break JZ4725B -> JZ4770 SoCs, the f0 plane is perfectly usable there.
>>>> Hm. I think it was your request/proposal to add this [1]?
>>> Because otherwise with your current patchset the f0 plane does not work *on JZ4780*.
>> Not that I am eager to fix that, but...
>> maybe it could be better to fix than having the check and -EINVAL depend on SoC compatible string
>> (or some new flag in soc_info. plane_f0_not_working)?
> 
> Totally agree! A proper fix would be much better. A "plane_f0_not_working" in the meantime is OK with me.

Ok, then I'll prepare a v13 with plane_f0_not_working.

> 
> Note that there are other things not working with your current implementation, for instance you cannot set the X/Y start position of the f1 plane, which means it's only really usable for fullscreen desktop/windows.

Is setting x/y possible for the other SoC?

> 
>>> It does work on older SoCs.
>>>> What I have forgotten is why the f0 plane should not be usable for jz4780.
>>> We return an error here to prevent userspace from using the f0 plane until it's effectively working on the JZ4780.
>> Well, what would be not working with that plane if user-space would try to use it?
> 
> From what I remember, it wouldn't show anything on screen, and after that trying to use the f1 plane wouldn't work either.

Ok. That may become a big project to fix. So let's do step 1 first.

BR and thanks,
NIkolaus