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Date:   Thu, 26 Aug 2021 11:14:07 +0200
From:   Daniel Vetter <daniel@ffwll.ch>
To:     Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Cc:     Daniel Vetter <daniel@ffwll.ch>,
        Yunfei Dong <yunfei.dong@mediatek.com>,
        dri-devel <dri-devel@lists.freedesktop.org>,
        Alexandre Courbot <acourbot@chromium.org>,
        Hans Verkuil <hverkuil-cisco@xs4all.nl>,
        Tzung-Bi Shih <tzungbi@chromium.org>,
        Tiffany Lin <tiffany.lin@mediatek.com>,
        Andrew-CT Chen <andrew-ct.chen@mediatek.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Tomasz Figa <tfiga@google.com>,
        Hsin-Yi Wang <hsinyi@chromium.org>,
        Fritz Koenig <frkoenig@chromium.org>,
        Irui Wang <irui.wang@mediatek.com>,
        linux-media <linux-media@vger.kernel.org>,
        devicetree <devicetree@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        srv_heupstream <srv_heupstream@mediatek.com>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@lists.infradead.org>,
        Project_Global_Chrome_Upstream_Group@mediatek.com,
        George Sun <george.sun@mediatek.com>
Subject: Re: [PATCH v5, 00/15] Using component framework to support multi
 hardware decode
Message-ID: <YSdbXzCJRsj/jsnl@phenom.ffwll.local>
Mail-Followup-To: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>,
        Yunfei Dong <yunfei.dong@mediatek.com>,
        dri-devel <dri-devel@lists.freedesktop.org>,
        Alexandre Courbot <acourbot@chromium.org>,
        Hans Verkuil <hverkuil-cisco@xs4all.nl>,
        Tzung-Bi Shih <tzungbi@chromium.org>,
        Tiffany Lin <tiffany.lin@mediatek.com>,
        Andrew-CT Chen <andrew-ct.chen@mediatek.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Tomasz Figa <tfiga@google.com>, Hsin-Yi Wang <hsinyi@chromium.org>,
        Fritz Koenig <frkoenig@chromium.org>,
        Irui Wang <irui.wang@mediatek.com>,
        linux-media <linux-media@vger.kernel.org>,
        devicetree <devicetree@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        srv_heupstream <srv_heupstream@mediatek.com>,
        "moderated list:ARM/Mediatek SoC support" <linux-mediatek@lists.infradead.org>,
        Project_Global_Chrome_Upstream_Group@mediatek.com,
        George Sun <george.sun@mediatek.com>
References: <20210811025801.21597-1-yunfei.dong@mediatek.com>
 <CAAEAJfDWOzCJxZFNtxeT7Cvr2pWbYrfz-YnA81sVNs-rM=8n4Q@mail.gmail.com>
 <CAKMK7uFW3Z=Up=OCJO4dNR9ffaTdFjHwoND9CrUw6LHmQ4t_AQ@mail.gmail.com>
 <CAAEAJfB3CoTU7bZe08wYEfTTm6=6UPOae9u39AtdbJ9saYknBA@mail.gmail.com>
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On Sun, Aug 22, 2021 at 02:57:15PM -0300, Ezequiel Garcia wrote:
> On Sun, 22 Aug 2021 at 13:50, Daniel Vetter <daniel@ffwll.ch> wrote:
> >
> > On Wed, Aug 18, 2021 at 4:12 PM Ezequiel Garcia
> > <ezequiel@vanguardiasur.com.ar> wrote:
> > >
> > > +danvet
> > >
> > > Hi,
> > >
> > > On Tue, 10 Aug 2021 at 23:58, Yunfei Dong <yunfei.dong@mediatek.com> wrote:
> > > >
> > > > This series adds support for multi hardware decode into mtk-vcodec, by first
> > > > adding component framework to manage each hardware information: interrupt,
> > > > clock, register bases and power. Secondly add core thread to deal with core
> > > > hardware message, at the same time, add msg queue for different hardware
> > > > share messages. Lastly, the architecture of different specs are not the same,
> > > > using specs type to separate them.
> > > >
> > >
> > > I don't think it's a good idea to introduce the component API in the
> > > media subsystem. It doesn't seem to be maintained, IRC there's not even
> > > a maintainer for it, and it has some issues that were never addressed.
> >
> > Defacto dri-devel folks are maintainer component.c, but also I'm not
> > aware of anything missing there?
> >
> 
> A while ago, I tried to fix a crash in the Rockchip DRM driver
> (I was then told there can be similar issues on the IMX driver too,
> but I forgot the details of that).
> 
> I sent a patchset trying to address it and got total silence back.
> Although you could argue the issue is in how drivers use the component
> API, AFAICR the abuse is spreaded across a few drivers, so it felt
> more reasonable to improve the component API itself, instead of changing
> all the drivers.
> 
> See below:
> 
> https://patchwork.kernel.org/project/linux-rockchip/cover/20200120170602.3832-1-ezequiel@collabora.com/

Patches get lost on the mailing list, and rockchip is one of the lesser
maintained drivers. You need to ping this stuff.

For bridge/panel I still think we should work towards removing component.c
use from them.

> > There has been discussions that in various drm subsystems like
> > drm_bridge or drm_panel a few things are missing, which prevent
> > drivers from moving _away_ from component.c to the more specific
> > solutions for panel/bridges. But nothing that's preventing them from
> > using component.c itself.
> >
> > I'm happy to merge a MAINTAINERS patch to clarify the situation if
> > that's needed.
> 
> Indeed, that would be good.

Ok I'm going to type something.
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch