Document the BL32 arg3 FDT passing to avoid confusions since OP-TEE expects the FDT via arg2 and not arg3. That the TF-A is shifting the arguments is not very obvious.
Signed-off-by: Marco Felsch <[email protected]> --- arch/arm/cpu/atf.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/arm/cpu/atf.c b/arch/arm/cpu/atf.c index d01e20508c7a..7abe43a2703e 100644 --- a/arch/arm/cpu/atf.c +++ b/arch/arm/cpu/atf.c @@ -158,6 +158,14 @@ struct bl2_to_bl31_params_mem_v2 *bl2_plat_get_bl31_params_v2(uintptr_t bl32_ent p.bl33_ep_info.args.arg0 = 0xffff & read_mpidr(); p.bl33_ep_info.pc = bl33_entry; + /* + * The FDT address is passed via arg3 to the BL32. The BL31 which is in + * charge to start the BL32, adapts this information and passes the FDT + * via arg2 to the BL32 in case of OP-TEE since OP-TEE expects the FDT + * within arg2. The reason for this behaviour is the TF-A legacy code + * path which uses arg0 to specify the SPSR (AARCH32, AARCH64) state. + * Therefore all OP-TEE call arguments are shifted by one. + */ p.bl32_ep_info.args.arg3 = fdt_addr; p.bl32_ep_info.pc = bl32_entry; -- 2.47.3
