[PATCH] Fix hang on reboot with Tegra2

This seems to be a regression in 2.6.37.

We cannot use writel() here since the resulting wmb() calls l2x0_cache_sync()
which uses a spinlock and L1 cache may be off at this point.

Change-Id: Ia23b317dee919055ff4abba1484735ea3165fd99
http://lists.infradead.org/pipermail/linux-arm-kernel/2011-February/041909.html

Signed-off-by: Simon Glass <sjg@chromium.org>
---
 arch/arm/mach-tegra/include/mach/system.h |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/arch/arm/mach-tegra/include/mach/system.h b/arch/arm/mach-tegra/include/mach/system.h
index 84d5d46..f1c0a79 100644
--- a/arch/arm/mach-tegra/include/mach/system.h
+++ b/arch/arm/mach-tegra/include/mach/system.h

@@ -33,7 +33,9 @@ static inline void arch_reset(char mode, const char *cmd)
 	void __iomem *reset = IO_ADDRESS(TEGRA_CLK_RESET_BASE + 0x04);
 	u32 reg = readl(reset);
 	reg |= 0x04;
-	writel(reg, reset);
+
+	/* use writel_related to avoid spinlock since L1 cache may be off */
+	writel_relaxed(reg, reset);
 }
 
 #endif

-- 
1.7.3.1

On Thu, Feb 17, 2011 at 8:13 AM, Simon Glass [off-list ref] wrote:

This seems to be a regression in 2.6.37.

Thanks, I'll put this in linux-tegra-2.6.37 and a modified version in
for-next, where arch_reset is in common.c.

We cannot use writel() here since the resulting wmb() calls l2x0_cache_sync()
which uses a spinlock and L1 cache may be off at this point.

I'm going to change the readl to readl_relaxed as well.

Change-Id: Ia23b317dee919055ff4abba1484735ea3165fd99

Upstream complains when they see these.