ARM: tegra: Fix hang on reboot

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.

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

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Colin Cross <ccross@android.com>

diff --git a/arch/arm/mach-tegra/common.c b/arch/arm/mach-tegra/common.c
index 34559d1..54826b8 100644 (file)
--- a/arch/arm/mach-tegra/common.c
+++ b/arch/arm/mach-tegra/common.c
@@ -39,9 +39,10 @@ void tegra_assert_system_reset(char mode, const char *cmd)
        void __iomem *reset = IO_ADDRESS(TEGRA_CLK_RESET_BASE + 0x04);
        u32 reg;
 
-       reg = readl(reset);
+       /* use *_related to avoid spinlock since caches are off */
+       reg = readl_relaxed(reset);
        reg |= 0x04;
-       writel(reg, reset);
+       writel_relaxed(reg, reset);
 }
 
 static __initdata struct tegra_clk_init_table common_clk_init_table[] = {