From mboxrd@z Thu Jan 1 00:00:00 1970 From: peter.chen@freescale.com (Peter Chen) Date: Fri, 7 Jun 2013 16:19:06 +0800 Subject: [PATCH v2 1/1] ARM: imx: clk-pllv3: change wait method for PLL lock Message-ID: <1370593146-14025-1-git-send-email-peter.chen@freescale.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org For some unknown reasons, the jiffies will be updated more than one tick at every short time. Eg, at this code: After timeout = jiffies + msecs_to_jiffies(10), the interrupt occurs, and the softirq 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 --- Changes for v2: - According to Russell King's suggestion, change code for more reasonable for timeout condition. - Change commit log. arch/arm/mach-imx/clk-pllv3.c | 14 ++++++++++---- 1 files changed, 10 insertions(+), 4 deletions(-) diff --git a/arch/arm/mach-imx/clk-pllv3.c b/arch/arm/mach-imx/clk-pllv3.c index d09bc3d..52e54df 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 @@ -48,7 +49,7 @@ 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); @@ -60,9 +61,14 @@ 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)) - return -ETIMEDOUT; + do { + if (readl_relaxed(pll->base) & BM_PLL_LOCK) + break; + udelay(100); + } while (count--); + + if (count == 0 && !(readl_relaxed(pll->base) & BM_PLL_LOCK)) + return -ETIMEDOUT; return 0; } -- 1.7.0.4