Re: [PATCH] OMAP3 clock: disable DPLL autoidle while waiting for DPLL to lock

[Tony Lindgren <tony@atomide.com>]

* Paul Walmsley <paul@pwsan.com> [081114 09:46]:
> 
> During _omap3_noncore_dpll_lock(), if a DPLL has no active downstream
> clocks and DPLL autoidle is enabled, the DPLL may never lock, since it
> will enter autoidle immediately.  To resolve this, disable DPLL
> autoidle while locking the DPLL, and unconditionally wait for the DPLL
> to lock.  This fixes some bugs where the kernel would hang when returning
> from retention or return the wrong rate for the DPLL.
> 
> This patch is a collaboration with Peter de Schrijver 
> <peter.de-schrijver@nokia.com> and Kevin Hilman 
> <khilman@deeprootsystems.com>.

Pushing to l-o tree today.

Tony


> Signed-off-by: Paul Walmsley <paul@pwsan.com>
> Cc: Peter de Schrijver <peter.de-schrijver@nokia.com>
> Cc: Kevin Hilman <khilman@deeprootsystems.com>
> ---
>  arch/arm/mach-omap2/clock34xx.c |   15 +++++----------
>  1 files changed, 5 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/arm/mach-omap2/clock34xx.c b/arch/arm/mach-omap2/clock34xx.c
> index 3a4e160..b8b4494 100644
> --- a/arch/arm/mach-omap2/clock34xx.c
> +++ b/arch/arm/mach-omap2/clock34xx.c
> @@ -163,19 +163,14 @@ static int _omap3_noncore_dpll_lock(struct clk *clk)
>  
>  	ai = omap3_dpll_autoidle_read(clk);
>  
> +	omap3_dpll_deny_idle(clk);
> +
>  	_omap3_dpll_write_clken(clk, DPLL_LOCKED);
>  
> -	if (ai) {
> -		/*
> -		 * If no downstream clocks are enabled, CM_IDLEST bit
> -		 * may never become active, so don't wait for DPLL to lock.
> -		 */
> -		r = 0;
> +	r = _omap3_wait_dpll_status(clk, 1);
> +
> +	if (ai)
>  		omap3_dpll_allow_idle(clk);
> -	} else {
> -		r = _omap3_wait_dpll_status(clk, 1);
> -		omap3_dpll_deny_idle(clk);
> -	};
>  
>  	return r;
>  }
> --
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