Hi Houlong,

On Mon, Aug 16, 2021 at 1:00 PM houlong wei [off-list ref] 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