ARM: iMX5: Don't enable DPLL if it already enabled

If the DPLL is already enabled, don't try to enable it again.
Since write to the DPLL control register will make the DPLL
reset and which will cause some issues when some child module
are sourced from this DPLL.

Signed-off-by: Jason Liu <jason.hui@linaro.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

diff --git a/arch/arm/mach-mx5/clock-mx51-mx53.c b/arch/arm/mach-mx5/clock-mx51-mx53.c
index 6b89c1b..0856482 100644 (file)
--- a/arch/arm/mach-mx5/clock-mx51-mx53.c
+++ b/arch/arm/mach-mx5/clock-mx51-mx53.c
@@ -271,7 +271,11 @@ static int _clk_pll_enable(struct clk *clk)
        int i = 0;
 
        pllbase = _get_pll_base(clk);
-       reg = __raw_readl(pllbase + MXC_PLL_DP_CTL) | MXC_PLL_DP_CTL_UPEN;
+       reg = __raw_readl(pllbase + MXC_PLL_DP_CTL);
+       if (reg & MXC_PLL_DP_CTL_UPEN)
+               return 0;
+
+       reg |= MXC_PLL_DP_CTL_UPEN;
        __raw_writel(reg, pllbase + MXC_PLL_DP_CTL);
 
        /* Wait for lock */