Some bootloaders set a cache cohenrency to a very slow mode. Use code from
Linux kernel to set it to "Cacheable, noncoherent, write-back, write
allocate".
Perfomance impact is significant on TP-Link EAP245 board, kernel
decompression time fall from 33 seconds to less than 1.
Signed-off-by: Julien Dusser <julien.dusser@free.fr>
mtc0 t0, CP0_STATUS
ehb
+ /*
+ * Some bootloaders set the 'Kseg0 coherency algorithm' to
+ * 'Cacheable, noncoherent, write-through, no write allocate'
+ * and this cause performance issues. Let's go and change it to
+ * 'Cacheable, noncoherent, write-back, write allocate'
+ */
+ mfc0 t0, CP0_CONFIG
+ li t1, ~7 #~CONF_CM_CMASK
+ and t0, t1
+ ori t0, 3 #CONF_CM_CACHABLE_NONCOHERENT
+ mtc0 t0, CP0_CONFIG
+ nop
+
mtc0 zero, CP0_COUNT
mtc0 zero, CP0_COMPARE
ehb