Received-SPF: pass (google.com: domain of linux-kernel+bounces-63172-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) client-ip=2604:1380:45e3:2400::1;
Date: Tue, 13 Feb 2024 11:04:40 +0200
From: Pekka Paalanen <pekka.paalanen@haloniitty.fi>
To: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Cc: Jyri Sarha <jyri.sarha@iki.fi>, Maarten Lankhorst
 <maarten.lankhorst@linux.intel.com>, Maxime Ripard <mripard@kernel.org>,
 Thomas Zimmermann <tzimmermann@suse.de>, David Airlie <airlied@gmail.com>,
 Daniel Vetter <daniel@ffwll.ch>, Sam Ravnborg <sam@ravnborg.org>, Devarsh
 Thakkar <devarsht@ti.com>, Aradhya Bhatia <a-bhatia1@ti.com>, Francesco
 Dolcini <francesco@dolcini.it>, Tomi Valkeinen <tomi.valkeinen@ti.com>,
 dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
 "wayland-devel@lists.freedesktop.org" <wayland-devel@lists.freedesktop.org>
Subject: Re: [PATCH 1/2] drm/tidss: Fix initial plane zpos values
Message-ID: <20240213110440.13af335a@eldfell>
In-Reply-To: <20240213-tidss-fixes-v1-1-d709e8dfa505@ideasonboard.com>
References: <20240213-tidss-fixes-v1-0-d709e8dfa505@ideasonboard.com>
	<20240213-tidss-fixes-v1-1-d709e8dfa505@ideasonboard.com>
Precedence: bulk
MIME-Version: 1.0
Content-Type: multipart/signed; boundary="Sig_/sNODGAuo=/Hxc1/SQ_PTM=+";
 protocol="application/pgp-signature"; micalg=pgp-sha256

--Sig_/sNODGAuo=/Hxc1/SQ_PTM=+
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: quoted-printable

On Tue, 13 Feb 2024 10:16:36 +0200
Tomi Valkeinen <tomi.valkeinen@ideasonboard.com> wrote:

> When the driver sets up the zpos property it sets the default zpos value
> to the HW id of the plane. That is fine as such, but as on many DSS
> versions the driver arranges the DRM planes in a different order than
> the HW planes (to keep the non-scalable planes first), this leads to odd
> initial zpos values. An example is J721e, where the initial zpos values
> for DRM planes are 1, 3, 0, 2.
>=20
> In theory the userspace should configure the zpos values properly when
> using multiple planes, and in that sense the initial zpos values
> shouldn't matter, but there's really no reason not to fix this and help
> the userspace apps which don't handle zpos perfectly. In particular,
> Weston seems to have issues dealing with the planes with the current
> default zpos values.
>=20
> So let's change the zpos values for the DRM planes to 0, 1, 2, 3.
>=20
> Another option would be to configure the planes marked as primary planes
> to zpos 0. On a two display system this would give us plane zpos values
> of 0, 0, 1, 2. The end result and behavior would be very similar in this
> option, and I'm not aware that this would actually help us in any way.
> So, to keep the code simple, I opted for the 0, 1, 2, 3 values.
>=20
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> Fixes: 32a1795f57ee ("drm/tidss: New driver for TI Keystone platform Disp=
lay SubSystem")

Hi Tomi,

have you reported this to Weston? What exactly is the problem?

It doesn't seem like a good idea to work around userspace bugs
(non-regression, I presume?) with kernel changes.


Thanks,
pq

> ---
>  drivers/gpu/drm/tidss/tidss_plane.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>=20
> diff --git a/drivers/gpu/drm/tidss/tidss_plane.c b/drivers/gpu/drm/tidss/=
tidss_plane.c
> index e1c0ef0c3894..68fed531f6a7 100644
> --- a/drivers/gpu/drm/tidss/tidss_plane.c
> +++ b/drivers/gpu/drm/tidss/tidss_plane.c
> @@ -213,7 +213,7 @@ struct tidss_plane *tidss_plane_create(struct tidss_d=
evice *tidss,
> =20
>  	drm_plane_helper_add(&tplane->plane, &tidss_plane_helper_funcs);
> =20
> -	drm_plane_create_zpos_property(&tplane->plane, hw_plane_id, 0,
> +	drm_plane_create_zpos_property(&tplane->plane, tidss->num_planes, 0,
>  				       num_planes - 1);
> =20
>  	ret =3D drm_plane_create_color_properties(&tplane->plane,
>=20


--Sig_/sNODGAuo=/Hxc1/SQ_PTM=+
Content-Type: application/pgp-signature
Content-Description: OpenPGP digital signature

-----BEGIN PGP SIGNATURE-----
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=iaMj
-----END PGP SIGNATURE-----

--Sig_/sNODGAuo=/Hxc1/SQ_PTM=+--