<html><body><p> <pre> Hi, Angelo: On Thu, 2024-07-25 at 11:46 +0200, AngeloGioacchino Del Regno wrote: > Il 05/07/24 11:28, CK Hu (胡俊光) ha scritto: > > On Tue, 2024-06-11 at 08:54 +0200, AngeloGioacchino Del Regno wrote: > > > Il 11/06/24 08:48, CK Hu (胡俊光) ha scritto: > > > > On Mon, 2024-06-10 at 10:28 +0200, AngeloGioacchino Del Regno wrote: > > > > > Il 06/06/24 07:29, CK Hu (胡俊光) ha scritto: > > > > > > Hi, Angelo: > > > > > > > > > > > > On Wed, 2024-06-05 at 13:15 +0200, AngeloGioacchino Del Regno wrote: > > > > > > > Il 05/06/24 03:38, CK Hu (胡俊光) ha scritto: > > > > > > > > Hi, Angelo: > > > > > > > > > > > > > > > > On Tue, 2024-05-21 at 09:57 +0200, AngeloGioacchino Del Regno wrote: > > > > > > > > > Document OF graph on MMSYS/VDOSYS: this supports up to three DDP paths > > > > > > > > > per HW instance (so potentially up to six displays for multi-vdo SoCs). > > > > > > > > > > > > > > > > > > The MMSYS or VDOSYS is always the first component in the DDP pipeline, > > > > > > > > > so it only supports an output port with multiple endpoints - where each > > > > > > > > > endpoint defines the starting point for one of the (currently three) > > > > > > > > > possible hardware paths. > > > > > > > > > > > > > > > > > > Reviewed-by: Rob Herring (Arm) <robh@kernel.org> > > > > > > > > > Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com> > > > > > > > > > Tested-by: Alexandre Mergnat <amergnat@baylibre.com> > > > > > > > > > Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> > > > > > > > > > --- > > > > > > > > > .../bindings/arm/mediatek/mediatek,mmsys.yaml | 28 +++++++++++++++++++ > > > > > > > > > 1 file changed, 28 insertions(+) > > > > > > > > > > > > > > > > > > diff --git a/Documentation/devicetree/bindings/arm/mediatek/mediatek,mmsys.yaml b/Documentation/devicetree/bindings/arm/mediatek/mediatek,mmsys.yaml > > > > > > > > > index b3c6888c1457..0ef67ca4122b 100644 > > > > > > > > > --- a/Documentation/devicetree/bindings/arm/mediatek/mediatek,mmsys.yaml > > > > > > > > > +++ b/Documentation/devicetree/bindings/arm/mediatek/mediatek,mmsys.yaml > > > > > > > > > @@ -93,6 +93,34 @@ properties: > > > > > > > > > '#reset-cells': > > > > > > > > > const: 1 > > > > > > > > > > > > > > > > > > + port: > > > > > > > > > + $ref: /schemas/graph.yaml#/properties/port > > > > > > > > > + description: > > > > > > > > > + Output port node. This port connects the MMSYS/VDOSYS output to > > > > > > > > > + the first component of one display pipeline, for example one of > > > > > > > > > + the available OVL or RDMA blocks. > > > > > > > > > + Some MediaTek SoCs support multiple display outputs per MMSYS. > > > > > > > > > > > > > > > > This patch looks good to me. Just want to share another information for you. > > > > > > > > Here is an example that mmsys/vdosys could point to the display interface node. > > > > > > > > > > > > > > > > vdosys0: syscon@1c01a000 { > > > > > > > > mmsys-display-interface = <&dsi0>, <&dsi1>, <&dp_intf0>; > > > > > > > > }; > > > > > > > > > > > > > > > > vdosys1: syscon@1c100000 { > > > > > > > > mmsys-display-interface = <&dp_intf1>; > > > > > > > > }; > > > > > > > > > > > > > > > > There is no conflict that mmsys/vdosys point to first component of one display pipeline or point to display interface. > > > > > > > > Both could co-exist. > > > > > > > > > > > > > > > > > > > > > > Hey CK, > > > > > > > > > > > > > > yes, this could be an alternative to the OF graphs, and I'm sure that it'd work, > > > > > > > even though this kind of solution would still require partial hardcoding of the > > > > > > > display paths up until mmsys-display-interface (so, up until DSI0, or DSI1, etc). > > > > > > > > > > > > > > The problem with a solution like this is that, well, even though it would work, > > > > > > > even if we ignore the suboptimal partial hardcoding, OF graphs are something > > > > > > > generic, while the mmsys-display-interface would be a MediaTek specific/custom > > > > > > > property. > > > > > > > > > > > > > > In the end, reusing generic kernel apis/interfaces/etc is always preferred > > > > > > > compared to custom solutions, especially in this case, in which the generic > > > > > > > stuff is on-par (or actually, depending purely on personal opinions, superior). > > > > > > > > > > > > > > As for the two to co-exist, I'm not sure that this is actually needed, as the > > > > > > > OF graphs are already (at the end of the graph) pointing to the display interface. > > > > > > > > > > > > > > In any case, just as a reminder: if there will be any need to add any custom > > > > > > > MediaTek specific properties later, it's ok and we can do that at any time. > > > > > > > > > > > > The alternative solution is using OF graphs to point display interface and use MediaTek specific property to first component: > > > > > > > > > > > > vdosys0: syscon@1c01a000 { > > > > > > ports { > > > > > > port@0 { > > > > > > endpoint { > > > > > > remote-endpoint = <&dsi0_endpoint>; > > > > > > }; > > > > > > }; > > > > > > > > > > > > port@1 { > > > > > > endpoint { > > > > > > remote-endpoint = <&dsi1_endpoint>; > > > > > > }; > > > > > > }; > > > > > > > > > > > > port@2 { > > > > > > endpoint { > > > > > > remote-endpoint = <&dp_intf0_endpoint>; > > > > > > }; > > > > > > }; > > > > > > }; > > > > > > > > > > > > display-first-component = <&ovl0>; > > > > > > }; > > > > > > > > > > > > And I agree to it's better to keep only OF graphs property, so it would be > > > > > > > > > > > > vdosys0: syscon@1c01a000 { > > > > > > ports { > > > > > > port@0 { > > > > > > endpoint { > > > > > > remote-endpoint = <&dsi0_endpoint>; > > > > > > > > > > > > }; > > > > > > }; > > > > > > > > > > > > port@1 { > > > > > > endpoint { > > > > > > remote-endpoint = <&dsi1_endpoint>; > > > > > > > > > > > > }; > > > > > > }; > > > > > > > > > > > > port@2 { > > > > > > endpoint { > > > > > > remote-endpoint = <&dp_intf0_endpoint>; > > > > > > } > > > > > > ; > > > > > > }; > > > > > > }; > > > > > > }; > > > > > > > > > > > > Maybe we could use OF graphs for both first component and display interface and drop using MediaTek specific property. > > > > > > > > > > > > > > > > We could, or we can simply walk through the OF Graph in the driver and get the > > > > > display interface like that, as it's board-specific ;-) > > > > > > > > > > ...but anyway, let's see that later: after getting this series upstreamed, I will > > > > > convert all MediaTek boards (including Chromebooks) to use the graphs instead, and > > > > > you'll see that, at least for the currently supported boards, there's no need for > > > > > any custom property. > > > > > > > > > > Also, setting the DSI0/1/dpintf endpoint to VDO0 is technically wrong, as that is > > > > > supposed to be the last one, and a graph is conceptually supposed to go from the > > > > > first to the last in sequence. > > > > > > > > > > *if* we will ever need (probably not) to get the VDO0 node to point directly to > > > > > the last node for whatever reason, the right way would be the first one you said, > > > > > so, mediatek,mmsys-display-interface = <&dsi0>, <&dsi1>, etc etc > > > > > > > > > > ...or mediatek,mmsys-possible-displays = < ... phandles > > > > > > > > > > > ...or anyway, many other solutions are possible - but again, I think this is not > > > > > the right time to think about that. Knowing that there are eventual solutions for > > > > > any need that might arise in the future is enough, IMO :-) > > > > > > > > This is one routing of display pipeline and the relation of VDOSYS0 with display pipeline. > > > > > > > > +-- VDOSYS0 ---------------------------------------------+ > > > > | | > > > > | | > > > > DRAM -> IOMMU ---> OVL0 -> RDMA0 -> ... -> DSC0 -> MERGE0 -> DP_INTF0 ----> > > > > | | > > > > | | > > > > +--------------------------------------------------------+ > > > > > > > > Video data is read by IOMMU from DRAM and send to display pipeline. Then video data travel through first component to display interface. > > > > VDOSYS0 manage each component in the pipeline include first component and display interface. > > > > The management include clock gating, reset, video data input/output routing. > > > > The relationship of VDOSYTS0 with first component is the same as the relationship of VDOSYS0 with display interface. > > > > If VDOSYS0 is not suitable using OF graph point to display interface, VDOSYS0 is also not suitable using OF graph point to first component. > > > > > > In the cases in which VDO goes directly to the display, it *is* possible to make it > > > point directly to the display. > > > > > > In the cases in which the pipeline is larger, VDO still points to the display, but > > > only later in the pipeline. > > Sorry I have just noticed your reply while looking for the status of this series. > > > I mean VDOSYS0 is not suitable 'using OF graph' to point to both display interface and first component. > > I seriously don't get why you're saying that VDOSYS0 is not suitable for OF Graphs > and I'm sorry but I suspect that the reason is that you don't understand the > concept of what a graph defines, other than how can it be walked through by design. > > > So VDOSYS0 should use specific property to point to both display interface and first component. > > Maybe > > > > vdosys0 { > > dma-device = <ovl0>; > > display-interface = <&dsi0>, <&dsi1>, <&dp_intf0>; > > }; > > What you just wrote here adds custom properties for no reason - as in, there is > no reason for vdosys0 to have two properties pointing one to the first component > and one to all of the possible display interfaces for vdosys0. vdosys has management relationship with these display device. The hardware relationship always exist even though I have no software reason. > Provided a graph, that graph does express the OVL0 relationship with VDO0, and > it does express the relationship between OVL0 and the final display interface > -> through expressing the relationship between OVL0 and all of the middle > components until reaching the actual display interface. <- > > Anyway, the proposed snippet either: > a. Invalidates the point of this series entirely, as in, graphs in this case are > implemented in order to stop hardcoding display paths for each board into the > driver; or > b. It is exactly the same as a graph, except with different properties and without > ports and endpoints. > > Moreover, there is no advantage in setting all of the possible display interfaces > that are connectable to VDOSYS0 in a display-interface property: > from a board-specific perspective, the board cares only about the interfaces that > are *available to that board*, and not about any other. I think in the board dts, the property could be overwritten. So the display interface list could be changed. > > If interfaces X and Y are available to a board, that board will have a graph for X > and a graph for Y, so they are both perfectly described with ... graphs! > > ...and even though the VDO0 (or the SoC, whatever) supports interface Z, if said > display interface is *not* present on the board, that interface will not be > described by any graph, because it does not pertain to that board, it's unused and > it's useless to describe (even though it would be possible to add it regardless of > whether it's usable or not on that board). > > Last thing - I don't know if you have this doubt or not, but for the sake of making > the stream of information complete: even dual-dsi displays can be described with a > graph without any issue. Here is my thought to make me accept this patch (I'm not sure you agree or not) dma-device and display-interface is used to point some specific device related to vdosys. OF graph is used to point to the display pipeline. Each has different meaning so each could co-exist. According to this thought, this patch is Reviewed-by: CK Hu <ck.hu@mediatek.com> > > > Regards, > Angelo > > > > > Regards, > > CK > > > > > > > > > The job of the component in display pipeline is to process the video data, > > > > but the job of VDOSYS0 is to manage (clock gating, reset, routing) the pipeline. > > > > If the OF graph is to show the video data travel path, VDOSYS0 should not exist in the OF graph. > > > > > > > > Regards, > > > > CK > > > > > > > > > > > > > > Cheers, > > > > > Angelo > > > > > > > > > > > Regards, > > > > > > CK > > > > > > > > > > > > > > > > > > > > Cheers! > > > > > > > Angelo > > > > > > > > > > > > > > > Regards, > > > > > > > > CK > > > > > > > > > > > > > > > > > + properties: > > > > > > > > > + endpoint@0: > > > > > > > > > + $ref: /schemas/graph.yaml#/properties/endpoint > > > > > > > > > + description: Output to the primary display pipeline > > > > > > > > > + > > > > > > > > > + endpoint@1: > > > > > > > > > + $ref: /schemas/graph.yaml#/properties/endpoint > > > > > > > > > + description: Output to the secondary display pipeline > > > > > > > > > + > > > > > > > > > + endpoint@2: > > > > > > > > > + $ref: /schemas/graph.yaml#/properties/endpoint > > > > > > > > > + description: Output to the tertiary display pipeline > > > > > > > > > + > > > > > > > > > + anyOf: > > > > > > > > > + - required: > > > > > > > > > + - endpoint@0 > > > > > > > > > + - required: > > > > > > > > > + - endpoint@1 > > > > > > > > > + - required: > > > > > > > > > + - endpoint@2 > > > > > > > > > + > > > > > > > > > required: > > > > > > > > > - compatible > > > > > > > > > - reg > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > </pre> </p></body></html><pre>************* MEDIATEK Confidentiality Notice ******************** The information contained in this e-mail message (including any attachments) may be confidential, proprietary, privileged, or otherwise exempt from disclosure under applicable laws. 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