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ARM: 6987/1: l2x0: fix disabling function to avoid deadlock 

The l2x0_disable function attempts to writel with the l2x0_lock held.
This results in deadlock when the writel contains an outer_sync call
for the platform since the l2x0_lock is already held by the disable
function. A further problem is that disabling the L2 without flushing it
first can lead to the spin_lock operation becoming visible after the
spin_unlock, causing any subsequent L2 maintenance to deadlock.

This patch replaces the writel with a call to writel_relaxed in the
disabling code and adds a flush before disabling in the control
register, preventing livelock from occurring.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Will Deacon 2011-07-01 14:36:19 +01:00 committed by Russell King
parent 186dcaa448
commit 38a8914f9a
1 changed files with 13 additions and 6 deletions
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19
arch/arm/mm/cache-l2x0.c
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@ -120,17 +120,22 @@ static void l2x0_cache_sync(void)
spin_unlock_irqrestore(&l2x0_lock, flags);
}
static void __l2x0_flush_all(void)
{
debug_writel(0x03);
writel_relaxed(l2x0_way_mask, l2x0_base + L2X0_CLEAN_INV_WAY);
cache_wait_way(l2x0_base + L2X0_CLEAN_INV_WAY, l2x0_way_mask);
cache_sync();
debug_writel(0x00);
}
static void l2x0_flush_all(void)
{
unsigned long flags;
/* clean all ways */
spin_lock_irqsave(&l2x0_lock, flags);
debug_writel(0x03);
writel_relaxed(l2x0_way_mask, l2x0_base + L2X0_CLEAN_INV_WAY);
cache_wait_way(l2x0_base + L2X0_CLEAN_INV_WAY, l2x0_way_mask);
cache_sync();
debug_writel(0x00);
__l2x0_flush_all();
spin_unlock_irqrestore(&l2x0_lock, flags);
}
@ -266,7 +271,9 @@ static void l2x0_disable(void)
unsigned long flags;
spin_lock_irqsave(&l2x0_lock, flags);
writel(0, l2x0_base + L2X0_CTRL);
__l2x0_flush_all();
writel_relaxed(0, l2x0_base + L2X0_CTRL);
dsb();
spin_unlock_irqrestore(&l2x0_lock, flags);
}