linux-kernel - Re: [PATCH 10/13] Do not try to disable hpet if it hasn't been initialized before

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Date:	Wed, 30 Jun 2010 13:53:43 -0400
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	stefano@...bellini.net, johnstul@...ibm.com
Cc:	linux-kernel@...r.kernel.org, xen-devel@...ts.xensource.com,
	Stefano.Stabellini@...citrix.com, sheng@...ux.intel.com,
	ddutile@...hat.com, jeremy@...p.org
Subject: Re: [PATCH 10/13] Do not try to disable hpet if it hasn't been
 initialized before

On Mon, Jun 21, 2010 at 05:14:04PM +0100, stefano@...bellini.net wrote:
> From: Stefano Stabellini <stefano.stabellini@...citrix.com>
> 
> hpet_disable is called unconditionally on machine reboot if hpet support
> is compiled in the kernel.
> hpet_disable only checks if the machine is hpet capable but doesn't make
> sure that hpet has been initialized.

CC-ing John Stultz who has had his head wrapped around this time-thingy.

Hi John!

What are your thoughts about this patch?
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@...citrix.com>
> ---
>  arch/x86/kernel/hpet.c |   18 ++++++++++--------
>  1 files changed, 10 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
> index 23b4ecd..2b299da 100644
> --- a/arch/x86/kernel/hpet.c
> +++ b/arch/x86/kernel/hpet.c
> @@ -959,16 +959,18 @@ fs_initcall(hpet_late_init);
>  
>  void hpet_disable(void)
>  {
> -	if (is_hpet_capable()) {
> -		unsigned int cfg = hpet_readl(HPET_CFG);
> +	unsigned int cfg;
>  
> -		if (hpet_legacy_int_enabled) {
> -			cfg &= ~HPET_CFG_LEGACY;
> -			hpet_legacy_int_enabled = 0;
> -		}
> -		cfg &= ~HPET_CFG_ENABLE;
> -		hpet_writel(cfg, HPET_CFG);
> +	if (!is_hpet_capable() || !hpet_address || !hpet_virt_address)
> +		return;
> +
> +	cfg = hpet_readl(HPET_CFG);
> +	if (hpet_legacy_int_enabled) {
> +		cfg &= ~HPET_CFG_LEGACY;
> +		hpet_legacy_int_enabled = 0;
>  	}
> +	cfg &= ~HPET_CFG_ENABLE;
> +	hpet_writel(cfg, HPET_CFG);
>  }
>  
>  #ifdef CONFIG_HPET_EMULATE_RTC
> -- 
> 1.7.0.4
> 
> --
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