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| author | Shinya Kuribayashi <skuribay@ruby.dti.ne.jp> | 2008-03-25 11:39:29 +0900 |
|---|---|---|
| committer | Shinya Kuribayashi <skuribay@ruby.dti.ne.jp> | 2008-03-25 11:39:29 +0900 |
| commit | e1390801a3c1a2b6d12fa90be368efc19f5b9bfd (patch) | |
| tree | bd17c0d102a57979894da20cdab6d2c006f2d979 /cpu | |
| parent | 0d48926c87ec96f974a6ac4034f4a2f2eab3255f (diff) | |
| download | u-boot-imx-e1390801a3c1a2b6d12fa90be368efc19f5b9bfd.zip u-boot-imx-e1390801a3c1a2b6d12fa90be368efc19f5b9bfd.tar.gz u-boot-imx-e1390801a3c1a2b6d12fa90be368efc19f5b9bfd.tar.bz2 | |
[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.S | 2 | ||||
| -rw-r--r-- | cpu/mips/start.S | 2 |
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) |