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;
Message-ID: <87cfcdfadee89984496c3f52d01b4f1e10c12cae.camel@collabora.com>
Subject: Re: Stateless Encoding uAPI Discussion and Proposal
From:   Nicolas Dufresne <nicolas.dufresne@collabora.com>
To:     Hsia-Jun Li <Randy.Li@synaptics.com>,
        Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Cc:     linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
        Hans Verkuil <hverkuil@xs4all.nl>,
        Sakari Ailus <sakari.ailus@iki.fi>,
        Andrzej Pietrasiewicz <andrzej.p@collabora.com>,
        Michael Tretter <m.tretter@pengutronix.de>,
        Jernej =?UTF-8?Q?=C5=A0krabec?= <jernej.skrabec@gmail.com>,
        Chen-Yu Tsai <wens@csie.org>,
        Samuel Holland <samuel@sholland.org>,
        Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Date:   Wed, 26 Jul 2023 15:53:58 -0400
In-Reply-To: <c15805b0-261b-114a-c29d-b63f00dd8da4@synaptics.com>
References: <ZK2NiQd1KnraAr20@aptenodytes>
         <c46d0c53b7e5dc8dcdf7925f3d892024390a8b2b.camel@collabora.com>
         <ZK6zjaJtulRSrn7P@aptenodytes>
         <bbd62e1b-dd0b-e351-110e-040b42d02974@synaptics.com>
         <ZL-8yBhWWChKBDHM@aptenodytes>
         <c15805b0-261b-114a-c29d-b63f00dd8da4@synaptics.com>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
User-Agent: Evolution 3.48.4 (3.48.4-1.fc38) 
MIME-Version: 1.0
Precedence: bulk

Hi,

Le mercredi 26 juillet 2023 =C3=A0 10:49 +0800, Hsia-Jun Li a =C3=A9crit=C2=
=A0:
> > I am strongly against this approach, instead I think we need to keep al=
l
> > vendor-specific parts in the kernel driver and provide a clean unified =
userspace
> > API.
> >=20
> We are driving away vendor participation. Besides, the current design is=
=20
> a performance bottleneck.

I know you have been hammering this argument for many many years. But in
concrete situation, we have conducted tests, and we out perform vendors sta=
cks
that directly hit into hardware register with stateless CODEC. Also, Paul's
proposal, is that fine grain / highly close to metal tuning of the encoding
process should endup in the Linux kernel, so that it can benefit from the
natural hard real-time advantage of a hard IRQ. Just like anything else, we=
 will
find a lot of common methods and shareable code which will benefit in secur=
ity
and quality, which is very unlike what we normally get from per vendor BSP.=
 The
strategy is the same as everything else in Linux, vendor will adpot it if t=
here
is a clear benefit. And better quality, ease of use, good collection of mat=
ure
userspace software is what makes the difference. It does takes time of cour=
se.

regards,
Nicolas