Re: [PATCH] Fix LPC32XX's clock.c

[Russell King - ARM Linux]

On Fri, Jan 27, 2012 at 03:17:48PM +0100, Roland Stigge wrote:
> @@ -382,30 +388,62 @@ static u32 local_clk_usbpll_setup(struct clk_pll_setup *pHCLKPllSetup)
>  static int local_usbpll_enable(struct clk *clk, int enable)
>  {
>  	u32 reg;
> -	int ret = -ENODEV;
> -	unsigned long timeout = 1 + msecs_to_jiffies(10);
> +	int ret = 0;
> +	unsigned long timeout = jiffies + msecs_to_jiffies(20);

...

> -		/* Wait for PLL lock */
> -		while ((timeout > jiffies) & (ret == -ENODEV)) {
> +		/*
> +		 * Enable PLL
> +		 */
> +		reg |= LPC32XX_CLKPWR_USBCTRL_PLL_PWRUP;
> +		__raw_writel(reg, LPC32XX_CLKPWR_USB_CTRL);
> +
> +		/*
> +		 * Wait for PLL to lock
> +		 */
> +		while ((timeout > jiffies) && (ret == -ENODEV)) {

This is buggy - it's waiting to go wrong when jiffies wraps.  You really
want to use time_before() or time_after() to make these comparisons, which
are safe against wrap-around.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/