The T-HEAD C90x PLIC has some special quirks, such as the S-mode
delegation bit. OpenSBI currently handles this by checking the compatible
string in the device tree.
However, this matching is done in the order of the fdt_match array. So if
a device tree contains both strings, for example:
compatible = "thead,c900-plic", "riscv,plic0";
Then OpenSBI will match against the generic "riscv,plic0" string, since
that appears first in the fdt_match array. This means it will fail to set
the S-mode delegation bit, and Linux will fail to boot. In some cases, it
is not possible to change the compatible string to just the T-HEAD PLIC,
as older versions of Linux only recognize the RISC-V compatible string.
This patch fixes that by moving the RISC-V string to the end, ensuring
that the more specific options get matched first.
Signed-off-by: Alex Studer <alex@studer.dev>
Reviewed-by: Anup Patel <anup@brainfault.org>
