MIPS: Preserve Config implementation-defined bits
The coprocessor 0 Config register includes 9 implementation defined
bits, which in some processors do things like enable write combining or
other functionality. We ought not to wipe them to 0 during boot. Rather
than doing so, preserve their value & only clear the bits standardised
by the MIPS architecture.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
diff --git a/arch/mips/cpu/start.S b/arch/mips/cpu/start.S
index 827a544..6aec430 100644
--- a/arch/mips/cpu/start.S
+++ b/arch/mips/cpu/start.S
@@ -123,8 +123,9 @@
mtc0 zero, CP0_COMPARE
#ifndef CONFIG_SKIP_LOWLEVEL_INIT
- /* CONFIG0 register */
- li t0, CONF_CM_UNCACHED
+ mfc0 t0, CP0_CONFIG
+ and t0, t0, MIPS_CONF_IMPL
+ or t0, t0, CONF_CM_UNCACHED
mtc0 t0, CP0_CONFIG
#endif