Re: [RFC PATCH v2 19/21] ARM: dts: exynos5250-arndale: add dsi and panel nodes

Tomi Valkeinen
2014-03-07T13:28:43Z

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On 07/03/14 15:07, Andrzej Hajda wrote:
> On 03/07/2014 01:32 PM, Tomi Valkeinen wrote:
>> On 07/03/14 14:22, Andrzej Hajda wrote:
>>
>>> I think we should even extend the bindings to fimd:
>>> dsi {
>>> port@0 {
>>> dsi_0: endpoint {
>>> remote-endpoint=<&fimd_0>;
>>> }
>>> }
>>> port@1 {
>>> dsi_1: endpoint {
>>> remote-endpoint=<&lvds_0>;
>>> }
>>> }
>>> }
>>>
>>> fimd {
>>> port@0 {
>>> fimd_0: endpoint {
>>> remote-endpoint=<&dsi_0>;
>>> }
>>> }
>>> }
>> If both fimd and dsi are SoC components, I don't see any strict need for
>> that. I think the ports/endpoints are only important when dealing with
>> external components, which can be used on any platform. For SoC internal
>> components you can have relevant data directly in the drivers, as it is
>> fixed (for that SoC).
>>
>> Of course, if using ports for SoC internal components makes things
>> easier for you, I don't see any problems with it either.
> There are many possible connections from FIMD, some of them:
> FIMD ---> RGB panel, external
> FIMD ---> DSI, on SoC
> FIMD ---> eDP, on SoC
> FIMD ---> ImageEnhacer, on SoC

This sounds similar to OMAP, at least roughly.

> In the first case port should be created.
> In other cases connection could be determined by presence/absence
> of specific nodes, so in fact the port can be optional, almost like in
> my proposal :)

Well, I think not.

In the external encoder case, the ports are there, and they are used.
You just didn't specify them, and thus make the driver deduce them from
the DT.

In the FIMD case, if the the RGB port is needed, you need to specify it
in the DT data, and it's used. If you only need, say, DSI, the RGB port
is not used and thus it doesn't need to be present in the DT data.

It's fine to leave the port definition out if it is not used at all.

>> For OMAP, the SoC's display blocks are all inside one bigger DSS
>> "container", so I have not seen need to represent the connections
>> between the internal components in the DT data.
> How do you deal with situation when IPs in SoC can be connected in
> different ways ?

Basically so that (using exynos terms) if, say DSI panel is to be
enabled, the DSI panel driver will reserve the DSI master for itself,
and the DSI master will reserve the FIMD for itself, presuming FIMD has
not already been reserved. When the DSI panel is disabled, FIMD is freed.

Tomi

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