firmware: fw_base: Remove CSR_MTVEC update check

Remove unnecessary CSR_MTVEC read to reduce the openSBI CSR requirement.

Mux are costly in FPGA. Allowing CSR_MTVEC to be write only is usefull
for the FMax/Area of FPGA softcore.

https://github.com/SpinalHDL/opensbi.git branch mtvec

Signed-off-by: Charles Papon <charles.papon.90@gmail.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>

diff --git a/firmware/fw_base.S b/firmware/fw_base.S
index cc6381d..07edc74 100644 (file)
--- a/firmware/fw_base.S
+++ b/firmware/fw_base.S
@@ -400,9 +400,6 @@ _start_warm:
        /* Setup trap handler */
        la      a4, _trap_handler
        csrw    CSR_MTVEC, a4
-       /* Make sure that mtvec is updated */
-1:     csrr    a5, CSR_MTVEC
-       bne     a4, a5, 1b
 
        /* Initialize SBI runtime */
        csrr    a0, CSR_MSCRATCH