Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Content-Type: text/plain;
        charset=us-ascii
Mime-Version: 1.0 (Mac OS X Mail 12.4 \(3445.104.21\))
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: <CYEO6R.2QDXEFO5G1WQ3@crapouillou.net>
Date:   Wed, 2 Feb 2022 13:17:14 +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>
Content-Transfer-Encoding: quoted-printable
Message-Id: <37CB6D86-4295-4281-BF3E-3E4B40E74196@goldelico.com>
References: <cover.1643632014.git.hns@goldelico.com>
 <6a7b188769a7ad477bf8cb71e1b9bc086b92388d.1643632014.git.hns@goldelico.com>
 <N7AO6R.7I6FABF106MT1@crapouillou.net>
 <1F27171F-DFCA-4707-8F50-D1A343F6D78E@goldelico.com>
 <CYEO6R.2QDXEFO5G1WQ3@crapouillou.net>
To:     Paul Cercueil <paul@crapouillou.net>
Precedence: bulk

Hi Paul,

> Am 02.02.2022 um 13:06 schrieb Paul Cercueil <paul@crapouillou.net>:
>=20
> Hi Nikolaus,
>=20
>>>> @@ -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]?
>=20
> 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)?

> It does work on older SoCs.
>=20
>> What I have forgotten is why the f0 plane should not be usable for =
jz4780.
>=20
> 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
> Cheers,
> -Paul

BR and thanks,
Nikolaus=