linux-kernel - Re: [PATCH v6 7/9] media: mtk-mdp: use mdp-rdma0 alias to point to MDP master

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Date:   Wed, 18 Aug 2021 23:34:32 +0800
From:   houlong wei <houlong.wei@...iatek.com>
To:     Eizan Miyamoto <eizan@...omium.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "wenst@...omium.org" <wenst@...omium.org>,
        Yong Wu (吴勇) 
        <Yong.Wu@...iatek.com>,
        "enric.balletbo@...labora.com" <enric.balletbo@...labora.com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "chunkuang.hu@...nel.org" <chunkuang.hu@...nel.org>,
        "Andrew-CT Chen (陳智迪)" 
        <Andrew-CT.Chen@...iatek.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        "Minghsiu Tsai (蔡明修)" 
        <Minghsiu.Tsai@...iatek.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>, <houlong.wei@...iatek.com>
Subject: Re: [PATCH v6 7/9] media: mtk-mdp: use mdp-rdma0 alias to point to
 MDP master

Hi Eizan,

Firstly, about how to determine the master mdp driver, we also can
judge the component type. The component type can be gotten by calling
of_device_get_match_data(dev). If the component is MTK_MDP_RDMA, it is
the master driver. No matter it is mdp_rdma0 or mdp_rdma1.

Secondly, about supporting the multiple MDP master device nodes, you
can try my advice in my previous comment after the completion of this
series of patches.

Thanks a lot.

Regards,
Houlong

On Wed, 2021-08-18 at 15:43 +0800, Eizan Miyamoto wrote:
> Hi Houlong,
> 
> On Mon, Aug 16, 2021 at 1:00 PM houlong wei <houlong.wei@...iatek.com
> > wrote:
> > Hi Eizan,
> > 
> > "mdp-rdma0" may be not the only one master device node. In fact,
> > there
> > are 2 "mdp-rdma" in mt8173. You can see "mdp_rdma1" via below link.
> > 
> > 
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/arch/arm64/boot/dts/mediatek/mt8173.dtsi?h=v5.13.11#n1016
> > If we add "mediatek,mt8173-mdp" to "mdp_rdma1" like below, we will
> > have
> > one more V4L2 video devie node.
> > 
> >                 mdp_rdma1: rdma@...02000 {
> >                         compatible = "mediatek,mt8173-mdp-rdma",
> >                                      "mediatek,mt8173-mdp";
> >                         ...
> >                 }
> > 
> > We should consider the case that there are more than one "MDP_RDMA"
> > components.
> 
> Would it be okay with you if we added support for multiple MDP master
> device nodes in follow-up changes? My rationale is this:
> - As far as I can tell, the mediatek integration with V4L2 currently
> only handles a single MDP master device node. It's not clear to me
> the
> scope of changes that will be needed to make things work properly
> with
> multiple nodes.
> - The patch series makes video decode work (admittedly, in light of
> your comments not optimally) upstream, which is better than not
> landing these changes at all.
> 
> I'd like to say that I'm very open to (and excited about) discussing
> further work to support multiple MDP master nodes, perhaps we can
> work together on this so I can understand what needs to be done.
> 
> Please let me know your thoughts,
> 
> Eizan