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authorShinya Kuribayashi <skuribay@ruby.dti.ne.jp>2008-03-25 11:39:29 +0900
committerShinya Kuribayashi <skuribay@ruby.dti.ne.jp>2008-03-25 11:39:29 +0900
commite1390801a3c1a2b6d12fa90be368efc19f5b9bfd (patch)
treebd17c0d102a57979894da20cdab6d2c006f2d979 /cpu
parent0d48926c87ec96f974a6ac4034f4a2f2eab3255f (diff)
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[MIPS] Request for the 'mips_cache_lock()' removal
The initial intension of having mips_cache_lock() was to use the cache as memory for temporary stack use so that a C environment can be set up as early as possible. But now mips_cache_lock() follow lowlevel_init(). We've already have the real memory initilaized at this point, therefore we could/should use it. No reason to lock at all. Other problems: Cache locking is not consistent across MIPS implementaions. Some imple- mentations don't support locking at all. The style of locking varies - some support per line locking, others per way, etc. Some parts use bits in status registers instead of cache ops. Current mips_cache_lock() is not necessarily general-purpose. And this is worthy of special mention; once U-Boot/MIPS locks the lines, they are never get unlocked, so the code relies on whatever gets loaded after U-Boot to re-initialize the cache and clear the locks. We're sup- posed to have CFG_INIT_RAM_LOCK and unlock_ram_in_cache() implemented, but leave the situation as it is for a long time. For these reasons, I proposed the removal of mips_cache_lock() from the global start-up code. This patch adds CFG_INIT_RAM_LOCK_MIPS to make existing users aware that *things have changed*. If he wants the same behavior as before, he needs to have CFG_INIT_RAM_LOCK_MIPS in his config file. If we don't have any regression report through several releases, then we'll remove codes entirely. Signed-off-by: Shinya Kuribayashi <skuribay@ruby.dti.ne.jp> Acked-by: Andrew Dyer <amdyer@gmail.com>
Diffstat (limited to 'cpu')
-rw-r--r--cpu/mips/cache.S2
-rw-r--r--cpu/mips/start.S2
2 files changed, 4 insertions, 0 deletions
diff --git a/cpu/mips/cache.S b/cpu/mips/cache.S
index 443240e..67ee19f 100644
--- a/cpu/mips/cache.S
+++ b/cpu/mips/cache.S
@@ -238,6 +238,7 @@ dcache_disable:
.end dcache_disable
+#ifdef CFG_INIT_RAM_LOCK_MIPS
/*******************************************************************************
*
* mips_cache_lock - lock RAM area pointed to by a0 in cache.
@@ -263,3 +264,4 @@ mips_cache_lock:
j ra
.end mips_cache_lock
+#endif /* CFG_INIT_RAM_LOCK_MIPS */
diff --git a/cpu/mips/start.S b/cpu/mips/start.S
index c92b162..930f9b3 100644
--- a/cpu/mips/start.S
+++ b/cpu/mips/start.S
@@ -267,10 +267,12 @@ reset:
/* Set up temporary stack.
*/
+#ifdef CFG_INIT_RAM_LOCK_MIPS
li a0, CFG_INIT_SP_OFFSET
la t9, mips_cache_lock
jalr t9
nop
+#endif
li t0, CFG_SDRAM_BASE + CFG_INIT_SP_OFFSET
la sp, 0(t0)