Hi Köry,
On 06/10/2023 19:47, Simon Glass wrote:
Hi Köry,
On Fri, 6 Oct 2023 at 07:26, Köry Maincent kory.maincent@bootlin.com wrote:
On Wed, 4 Oct 2023 15:39:23 +0300 Roger Quadros rogerq@kernel.org wrote:
Hello, Thanks for adding me in cc. Also it seems I forgot to add myself to MAINTAINERS for the extension_board.c file.
Before this goes too far I think this should move to using a linker list to declare the driver (or a driver-model driver if you prefer, but that might be overkill).
So I've been working on this on the side and got linker list way working with custom script booting but as soon as I move to standard boot flow it no longer works. This is because there is no code in place to apply the overlay and pass it to next stage e.g. EFI.
I see the following note at https://elixir.bootlin.com/u-boot/latest/source/boot/bootmeth_efi.c#L304
" /* * TODO: Apply extension overlay * * Here we need to load and apply the extension overlay. This is * not implemented. See do_extension_apply(). The extension * stuff needs an implementation in boot/extension.c so it is * separate from the command code. Really the extension stuff * should use the device tree and a uclass / driver interface * rather than implementing its own list */ "
I agreed that the extension implementation should move in boot/extension.c or common for general use. I am wondering what the advantage of creating an uclass interface? I am not an uclass expert but there is no per driver ops and usage. What do you dislike about using its own list?
I looked at this briefly for bootstd and left it alone, partly for this reason.
The operations I know about are:
- scan for extension boards to produce a list: needs to happen at
start of 'bootflow scan' I think)
- applying relevant overlays: needs to happen in the read_bootflow()
method perhaps
- listing available extensions
I think a uclass makes sense, along with separating out the 'extension' command from the actual functionality.
What do you think about this? OK to move extension card driver to uclass?
Another note at https://elixir.bootlin.com/u-boot/latest/source/cmd/extension_board.c#L198
"/* extensions should have a uclass - for now we use UCLASS_SIMPLE_BUS uclass */"
So are we better off implementing a class driver for extension stuff?
I think the first point should be to move it in common or boot and makes it generic for using the extension function everywhere. I will let Simon answer about the uclass part.
I believe this relates to boot/
Regards,
Regards, Simon