From mboxrd@z Thu Jan 1 00:00:00 1970 From: peter.chen@freescale.com (Peter Chen) Date: Thu, 6 Jun 2013 14:55:26 +0800 Subject: [PATCH 1/1] ARM: imx: clk-pllv3: change wait method for PLL lock Message-ID: <1370501726-7421-1-git-send-email-peter.chen@freescale.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org For tickless system, the jiffies may be updated long time (>20ms). At high loading system, the current waiting method will cause waiting timeout, and cause a kernel dump at below case. After timeout = jiffies + msecs_to_jiffies(10), the timer interrupt occurs, it updates jiffies (eg, + 2 jiffies), then return back from interrupt, the time between above operations are tiny, the PLL is still not locked, but the timeout condition is satisfied. Signed-off-by: Peter Chen --- arch/arm/mach-imx/clk-pllv3.c | 9 ++++++--- 1 files changed, 6 insertions(+), 3 deletions(-) diff --git a/arch/arm/mach-imx/clk-pllv3.c b/arch/arm/mach-imx/clk-pllv3.c index 36aac94..eefc6c2 100644 --- a/arch/arm/mach-imx/clk-pllv3.c +++ b/arch/arm/mach-imx/clk-pllv3.c @@ -16,6 +16,7 @@ #include #include #include +#include #include "clk.h" #define PLL_NUM_OFFSET 0x10 @@ -50,7 +51,7 @@ struct clk_pllv3 { static int clk_pllv3_prepare(struct clk_hw *hw) { struct clk_pllv3 *pll = to_clk_pllv3(hw); - unsigned long timeout = jiffies + msecs_to_jiffies(10); + int count = 100; u32 val; val = readl_relaxed(pll->base); @@ -62,9 +63,11 @@ static int clk_pllv3_prepare(struct clk_hw *hw) writel_relaxed(val, pll->base); /* Wait for PLL to lock */ - while (!(readl_relaxed(pll->base) & BM_PLL_LOCK)) - if (time_after(jiffies, timeout)) + while (!(readl_relaxed(pll->base) & BM_PLL_LOCK)) { + udelay(100); + if (--count == 0) return -ETIMEDOUT; + } return 0; } -- 1.7.0.4