[PATCH v2 1/1] ARM: imx: clk-pllv3: improve the timeout waiting method

[Sascha Hauer]

On Tue, Jul 16, 2013 at 10:23:20AM +0800, Peter Chen wrote:
> There are two improvements for this commit:
> 
> - Add comparing pll lock condition after while loop. It can
> fix potential fake timeout problem caused by the code is just
> scheduled out before compare the timeout, and the time of
> scheduling out are more than one jiffies.
> 
> - Move timeout assignment more close to compare the timeout.
> It can reduce the possibility the code is scheduled out, and
> the timeout can be more precise.
> 
> Signed-off-by: Peter Chen <peter.chen at freescale.com>

Acked-by: Sascha Hauer <s.hauer at pengutronix.de>

Sascha

> ---
> 
> Changes for v2:
> - Add more description for this improvement according to
> Fabio's suggstion.
> - Add comparsion after while loop according to Sascha's
> suggestion.
> 
>  arch/arm/mach-imx/clk-pllv3.c |   15 +++++++++++----
>  1 files changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm/mach-imx/clk-pllv3.c b/arch/arm/mach-imx/clk-pllv3.c
> index 36aac94..4499db5 100644
> --- a/arch/arm/mach-imx/clk-pllv3.c
> +++ b/arch/arm/mach-imx/clk-pllv3.c
> @@ -50,7 +50,7 @@ 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);
> +	unsigned long timeout;
>  	u32 val;
>  
>  	val = readl_relaxed(pll->base);
> @@ -61,12 +61,19 @@ static int clk_pllv3_prepare(struct clk_hw *hw)
>  		val &= ~BM_PLL_POWER;
>  	writel_relaxed(val, pll->base);
>  
> +	timeout = jiffies + msecs_to_jiffies(10);
>  	/* Wait for PLL to lock */
> -	while (!(readl_relaxed(pll->base) & BM_PLL_LOCK))
> +	do {
> +		if (readl_relaxed(pll->base) & BM_PLL_LOCK)
> +			break;
>  		if (time_after(jiffies, timeout))
> -			return -ETIMEDOUT;
> +			break;
> +	} while (1);
>  
> -	return 0;
> +	if (readl_relaxed(pll->base) & BM_PLL_LOCK)
> +		return 0;
> +	else
> +		return -ETIMEDOUT;
>  }
>  
>  static void clk_pllv3_unprepare(struct clk_hw *hw)
> -- 
> 1.7.0.4
> 
> 
> 
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> 

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