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Subject: Re: [PATCH v12 2/9] drm/ingenic: Add support for JZ4780 and HDMI
 output
From:   "H. Nikolaus Schaller" <hns@goldelico.com>
In-Reply-To: <5ZFO6R.M6Z7S3EBA1YC1@crapouillou.net>
Date:   Wed, 2 Feb 2022 13:33:15 +0100
Cc:     Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        Kees Cook <keescook@chromium.org>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Neil Armstrong <narmstrong@baylibre.com>,
        Robert Foss <robert.foss@linaro.org>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        Jernej Skrabec <jernej.skrabec@gmail.com>,
        Harry Wentland <harry.wentland@amd.com>,
        Sam Ravnborg <sam@ravnborg.org>,
        Maxime Ripard <maxime@cerno.tech>,
        Hans Verkuil <hverkuil-cisco@xs4all.nl>,
        Liam Girdwood <lgirdwood@gmail.com>,
        Mark Brown <broonie@kernel.org>,
        Paul Boddie <paul@boddie.org.uk>,
        Andrzej Hajda <andrzej.hajda@intel.com>,
        Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>,
        devicetree@vger.kernel.org, linux-mips@vger.kernel.org,
        linux-kernel@vger.kernel.org, letux-kernel@openphoenux.org,
        Jonas Karlman <jonas@kwiboo.se>,
        dri-devel@lists.freedesktop.org,
        Ezequiel Garcia <ezequiel@collabora.com>
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To:     Paul Cercueil <paul@crapouillou.net>
Precedence: bulk


> Am 02.02.2022 um 13:28 schrieb Paul Cercueil <paul@crapouillou.net>:
>=20
>=20
>=20
> Le mer., f=C3=A9vr. 2 2022 at 13:17:14 +0100, H. Nikolaus Schaller =
<hns@goldelico.com> a =C3=A9crit :
>> Hi Paul,
>>> Am 02.02.2022 um 13:06 schrieb Paul Cercueil <paul@crapouillou.net>:
>>> Hi Nikolaus,
>>>>>> @@ -446,6 +454,9 @@ static int =
ingenic_drm_plane_atomic_check(struct drm_plane *plane,
>>>>>> 	if (!crtc)
>>>>>> 		return 0;
>>>>>> +	if (plane =3D=3D &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)?
>=20
> 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.

>=20
> 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?

>=20
>>> 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?
>=20
> =46rom 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