Rob Herring <robh@xxxxxxxxxx> writes: > On Thu, Nov 16, 2023 at 3:36 AM Javier Martinez Canillas > <javierm@xxxxxxxxxx> wrote: [...] >> > >> > This is the opposite of what we do for memory and memory reservations. >> > EFI is the source of truth for those. >> > >> > This could also lead to an interesting scenario. As simple-framebuffer >> > can define its memory in a /reserved-memory node, but that is ignored >> > in EFI boot. Probably would work, but only because EFI probably >> > generates its memory map table from the /reserved-memory nodes. >> > >> >> I see. So what would be the solution then? Ignoring creating a platform >> device for "simple-framebuffer" if booted using EFI and have an EFI-GOP? > > Shrug. I don't really know anything more about EFI FB, but I would > guess it can't support handling resources like clocks, power domains, > regulators, etc. that simple-fb can. So if a platform needs those, do That's correct, and the reason why I thought that the DTB would be the single source of truth for the firmware provided framebuffer. For example, in some arm platforms that u-boot does provide an EFI-GOP, you need to boot with clk_ignore_unused or the system framebuffer just goes away once the unused clocks are gated. Same for PD, regulators, etc. > we say they should not setup EFI-GOP? Or is there a use case for > having both? Clients that don't muck with resources can use EFI-GOP > and those that do use simple-fb. For example, does/can grub use > EFI-GOP, but not simple-fb? > I don't think grub can use the simple-fb, it can use the EFI-GOP if is available though. And things work because of course grub won't try to disable unused resources like Linux does. > Rob > -- Best regards, Javier Martinez Canillas Core Platforms Red Hat
