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From:   Jernej =?utf-8?B?xaBrcmFiZWM=?= <jernej.skrabec@gmail.com>
To:     Dmitry Osipenko <dmitry.osipenko@collabora.com>,
        =?ISO-8859-1?Q?Cl=E9ment_P=E9ron?= <peron.clem@gmail.com>
Cc:     Chen-Yu Tsai <wens@csie.org>, Samuel Holland <samuel@sholland.org>,
        linux-sunxi@lists.linux.dev,
        linux-kernel <linux-kernel@vger.kernel.org>,
        devicetree <devicetree@vger.kernel.org>
Subject: Re: [PATCH v1] ARM: dts: sun8i: h3: orangepi-pc: Add CMA reserved memory node
Date:   Wed, 14 Sep 2022 20:34:49 +0200
Message-ID: <1826631.tdWV9SEqCh@jernej-laptop>
In-Reply-To: <CAJiuCcefkre611=1UXEkwScN+bYSBhE_ivGzTK7ZMvp-j4MbRQ@mail.gmail.com>
References: <20220914151125.212876-1-dmitry.osipenko@collabora.com> <CAJiuCcefkre611=1UXEkwScN+bYSBhE_ivGzTK7ZMvp-j4MbRQ@mail.gmail.com>
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Dne sreda, 14. september 2022 ob 17:33:27 CEST je Cl=E9ment P=E9ron napisal=
(a):
> Hi Dmitry,
>=20
> On Wed, 14 Sept 2022 at 17:12, Dmitry Osipenko
>=20
> <dmitry.osipenko@collabora.com> wrote:
> > Add 256MB CMA node to the Orange Pi PC board. This fixes memory allocat=
ion
> > failures for Cedrus video decoder on trying to play a 1080p video with
> > gstreamer.
> >=20
> > Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
> > ---
> >=20
> >  arch/arm/boot/dts/sun8i-h3-orangepi-pc.dts | 14 ++++++++++++++
> >  1 file changed, 14 insertions(+)
> >=20
> > diff --git a/arch/arm/boot/dts/sun8i-h3-orangepi-pc.dts
> > b/arch/arm/boot/dts/sun8i-h3-orangepi-pc.dts index
> > b96e015f54ee..e655346a9fb4 100644
> > --- a/arch/arm/boot/dts/sun8i-h3-orangepi-pc.dts
> > +++ b/arch/arm/boot/dts/sun8i-h3-orangepi-pc.dts
> > @@ -60,6 +60,20 @@ chosen {
> >=20
> >                 stdout-path =3D "serial0:115200n8";
> >        =20
> >         };
> >=20
> > +       reserved-memory {
> > +               #address-cells =3D <1>;
> > +               #size-cells =3D <1>;
> > +               ranges;
> > +
> > +               linux,cma@40000000 {
> > +                       compatible =3D "shared-dma-pool";
> > +                       alloc-ranges =3D <0x40000000 0x40000000>;
> > +                       size =3D <0x10000000>; /* 256MiB */
> > +                       linux,cma-default;
> > +                       reusable;
> > +               };
> > +       };
> > +
>=20
> This change seems legit for all H3 boards and could be moved to the H3 dt=
si,
> no?

That's true. However, there is a reason why this node doesn't exist. One or=
=20
two H2+ boards (which use H3 dtsi) have only 256 MiB of RAM, so this can't=
=20
work with them. A few H3 boards have 512 MiB of RAM, so you eat basically h=
alf=20
of the RAM with that. Additionally, contrary to A20 and similar SoCs, which=
=20
have such node, Cedrus can address whole RAM, so this is not strictly neede=
d.=20
It's better to leave this decision to distribution. Some don't care about=20
Cedrus and some do a lot. Default size can be set via kernel config and it =
can=20
be overriden by kernel argument if necessary.

Best regards,
Jernej

>=20
> Regards,
> Clement
>=20
> >         connector {
> >        =20
> >                 compatible =3D "hdmi-connector";
> >                 type =3D "a";
> >=20
> > --
> > 2.37.3