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: <52c9cf205a6b107175225733e4bff0d29c9d86c1.camel@collabora.com>
Subject: Re: [PATCH 0/6] media: mediatek-vcodec: Fix capability fields again
From:   Nicolas Dufresne <nicolas.dufresne@collabora.com>
To:     Chen-Yu Tsai <wenst@chromium.org>
Cc:     Tiffany Lin <tiffany.lin@mediatek.com>,
        Andrew-CT Chen <andrew-ct.chen@mediatek.com>,
        Yunfei Dong <yunfei.dong@mediatek.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Hans Verkuil <hverkuil-cisco@xs4all.nl>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-mediatek@lists.infradead.org,
        Matthias Brugger <matthias.bgg@gmail.com>
Date:   Mon, 04 Jul 2022 15:01:17 -0400
In-Reply-To: <CAGXv+5Hrc6RageAu1YMBCA22r0kz+-C+9qO=qdDEmn_QhSCB3w@mail.gmail.com>
References: <20220701105237.932332-1-wenst@chromium.org>
         <e601a375-cc80-40cd-9791-e44e9d37cec0@email.android.com>
         <CAGXv+5Hrc6RageAu1YMBCA22r0kz+-C+9qO=qdDEmn_QhSCB3w@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
User-Agent: Evolution 3.44.2 (3.44.2-1.fc36) 
MIME-Version: 1.0
Precedence: bulk

Le vendredi 01 juillet 2022 =C3=A0 21:10 +0800, Chen-Yu Tsai a =C3=A9crit=
=C2=A0:
> On Fri, Jul 1, 2022 at 8:45 PM Nicolas Dufresne
> <nicolas.dufresne@collabora.com> wrote:
> >=20
> > Hi Chen,
> >=20
> > Le 1 juill. 2022 06 h 52, Chen-Yu Tsai <wenst@chromium.org> a =C3=A9cri=
t :
> >=20
> > Hi everyone,
> >=20
> > The previous round of changes to the mtk-vcodec driver's returned
> > capabilities caused some issues for ChromeOS. In particular, the
> > ChromeOS stateless video decoder uses the "Driver Name" field to
> > match a video device to its media device. As the field was only
> > changed for the video device and not the media device, a match
> > could no longer be found.
> >=20
> >=20
> > This match is not specified in the spec. If you feel like it should, pe=
rhaps consider specifying it first. To me it's nice if they match, but it's=
 for now just cosmetic.
>=20
> Right. Even for cosmetic reasons I think my changes make sense though.
> Fixing the matching is another thing.
>=20
> > Though this requires some discussion, as userland is expected to enumer=
ate the media device and find the video device by walking the topology. Thi=
s is the only specified way to match both.
>=20
> AFAICT, v4l2-ctl does similar matching, though by bus_info. Maybe it's
> out of convenience?

bus_info has indeed been used a lot in the past, it will be more reliable t=
hen
"driver name" matching. Using topology remains the recommended identificati=
on
method.

>=20
> ChenYu
>=20
> >=20
> >=20
> > While fixing this, I found that the current info used for the fields
> > don't make a lot of sense, and tried to fix them in this series.
> >=20
> > Patch 1 reverts the driver name field change. It also makes it
> > explicit that the field really should match the driver name.
> >=20
> > Patch 2 changes the value for the card name, making it a free form
> > string that includes the SoC model.
> >=20
> > Patch 3 removes setting the bus_info field, instead using the default
> > value derived from the underlying |struct device| as set by the V4L2
> > core.
> >=20
> > Patches 4 through 6 do the same as 1 through 3 respectively, but for
> > the encoder side.
> >=20
> > This series is based on next-20220701, and was tested on mainline on
> > MT8183 Juniper, and on ChromeOS v5.10, on which we have a whole bunch
> > of backports pending, on MT8195 Tomato.
> >=20
> > Please have a look.
> >=20
> >=20
> > Thanks
> > ChenYu
> >=20
> > Chen-Yu Tsai (6):
> >   media: mediatek: vcodec: Revert driver name change in decoder
> >     capabilities
> >   media: mediatek: vcodec: Use meaningful decoder card name including
> >     chip name
> >   media: mediatek: vcodec: Use default bus_info for decoder capability
> >   media: mediatek: vcodec: Revert driver name change in encoder
> >     capabilities
> >   media: mediatek: vcodec: Use meaningful encoder card name including
> >     chip name
> >   media: mediatek: vcodec: Use default bus_info for encoder capability
> >=20
> > drivers/media/platform/mediatek/vcodec/mtk_vcodec_dec.c | 7 ++++---
> > drivers/media/platform/mediatek/vcodec/mtk_vcodec_drv.h | 1 +
> > drivers/media/platform/mediatek/vcodec/mtk_vcodec_enc.c | 7 ++++---
> > 3 files changed, 9 insertions(+), 6 deletions(-)
> >=20
> > --
> > 2.37.0.rc0.161.g10f37bed90-goog
> >=20
> >=20