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

From: houlong wei <houlong.wei@mediatek.com>
To: Eizan Miyamoto <eizan@chromium.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"wenst@chromium.org" <wenst@chromium.org>,
	"Yong Wu (吴勇)" <Yong.Wu@mediatek.com>,
	"enric.balletbo@collabora.com" <enric.balletbo@collabora.com>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"chunkuang.hu@kernel.org" <chunkuang.hu@kernel.org>,
	"Andrew-CT Chen (陳智迪)" <Andrew-CT.Chen@mediatek.com>,
	"Matthias Brugger" <matthias.bgg@gmail.com>,
	"Mauro Carvalho Chehab" <mchehab@kernel.org>,
	"Minghsiu Tsai (蔡明修)" <Minghsiu.Tsai@mediatek.com>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"linux-media@vger.kernel.org" <linux-media@vger.kernel.org>,
	"linux-mediatek@lists.infradead.org"
	<linux-mediatek@lists.infradead.org>,
	houlong.wei@mediatek.com
Subject: Re: [PATCH v6 7/9] media: mtk-mdp: use mdp-rdma0 alias to point to MDP master
Date: Wed, 18 Aug 2021 23:34:32 +0800	[thread overview]
Message-ID: <ea8c8373fbf6a9895276f098cfa2cf3f7761a4b5.camel@mediatek.com> (raw)
In-Reply-To: <CAOak1e-oyzxbvHimMReQpZCAPyCtAsaGixjwmoa0EzMjqaUxVg@mail.gmail.com>

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@mediatek.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@14002000 {
> >                         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