Hi Prabhakar, On Wed, Feb 19, 2020 at 12:25:37PM +0000, Lad, Prabhakar wrote: > On Wed, Feb 19, 2020 at 12:08 PM Laurent Pinchart wrote: > > On Wed, Feb 19, 2020 at 11:42:42AM +0000, Lad, Prabhakar wrote: > > > Hi, > > > > > > I am working Renesas RZ/Gx platforms, these boards have support for > > > connecting MIPI adapter mezzanine board [1]. To enable this support I > > > am planning to create a dtsi which will include the board file and > > > enable the necessary VIN/CSI and the camera endpoint. > > > > > > For example: to add support for G2E board I would create a file named > > > r8a774c0-cat874-mipi-adapter.dtsi which will include the board file > > > r8a774c0.dtsi and enable necessary VIN/CSI/Camera endpoint and when > > > user wants to enable this support for the G2E board he could just > > > include r8a774c0-cat874-mipi-adapter.dtsi to r8a774c0-cat874.dts > > > > > > Would this be a good approach or is there an alternative way which I am missing. > > > > DT overlays are another option. They can't be applied on a running > > system though. It doesn't seem like the mezzanine boards can be detected > > by the boot loader, so overlays can't be applied automatically before > > the kernel is started. One option would still be to provide them to > > U-Boot and apply a selected overlay based on environment variables. > > Another option would be to apply overlays as part of the build process, > > which shouldn't require modifying the DT sources to #include the .dtsi > > file for the mezzanine board. > > Thank you for the insight, overlay is something which I wanted to > avoid and have the dtb as part of kernel itself. How about just > creating r8a774c0-cat874-mipi-adapter.dts which would include > r8a774c0-cat874.dts file and enable the VIN/CSI/Camera endpoint, so > the user would just use r8a774c0-cat874-mipi-adapter.dtb file when the > mipi adapter is connected ? That would restrict usage of the mezzanine board to a particular base board, while in the general case there could be different types of base boards compatible with a set of mezzanines. The reason why I mentioned overlay isn't really to apply them dynamically, but for the set of tools around them. Bootloaders can apply overlays, and we can also apply overlays to a DTB as part of a build process, without patching the source. Is there a particular reason why you would prefer avoiding them ? > > > [1] https://github.com/Kevin-WSCU/96Boards-Camera/blob/master/AISTARVISION%20MIPI%20Adapter%20V2.1/AISTARVISION%20MIPI%20Adapter%20V2.1.pdf -- Regards, Laurent Pinchart
