[U-Boot] [PATCH 04/10] arm: mvebu: Flush caches and disable MMU only on A38x

Stefan Roese
2015-07-23T08:26:14Z

Only with disabled MMU its possible to switch the base register address
on Armada 38x. Without this the SDRAM located at >= 0x4000.0000 is also
not accessible, as its still locked to cache.

So to fully release / unlock this area from cache, we need to first
flush all caches, then disable the MMU and disable the L2 cache.

On Armada XP this does not seem to be needed. Even worse, with this
code added, I sometimes see strange input charactes loss from the
console.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Luka Perkov <luka.perkov@sartura.hr>
---
arch/arm/mach-mvebu/cpu.c | 26 +++++++++++++++++++-------
1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/arch/arm/mach-mvebu/cpu.c b/arch/arm/mach-mvebu/cpu.c
index 7335620..23c2a97 100644
--- a/arch/arm/mach-mvebu/cpu.c
+++ b/arch/arm/mach-mvebu/cpu.c
@@ -183,13 +183,25 @@ static void set_cbar(u32 addr)
int arch_cpu_init(void)
{
#ifndef CONFIG_SPL_BUILD
- /*
- * Only with disabled MMU its possible to switch the base
- * register address on Armada 38x. Without this the SDRAM
- * located at >= 0x4000.0000 is also not accessible, as its
- * still locked to cache.
- */
- mmu_disable();
+ if (mvebu_soc_family() == MVEBU_SOC_A38X) {
+ struct pl310_regs *const pl310 =
+ (struct pl310_regs *)CONFIG_SYS_PL310_BASE;
+
+ /*
+ * Only with disabled MMU its possible to switch the base
+ * register address on Armada 38x. Without this the SDRAM
+ * located at >= 0x4000.0000 is also not accessible, as its
+ * still locked to cache.
+ *
+ * So to fully release / unlock this area from cache, we need
+ * to first flush all caches, then disable the MMU and
+ * disable the L2 cache.
+ */
+ icache_disable();
+ dcache_disable();
+ mmu_disable();
+ clrbits_le32(&pl310->pl310_ctrl, L2X0_CTRL_EN);
+ }
#endif

/* Linux expects the internal registers to be at 0xf1000000 */
--
2.4.6