From mboxrd@z Thu Jan  1 00:00:00 1970
From: Wei Wang <wei.wang2@amd.com>
Subject: Re: [PATCH] acpi: do not flush cache if cx->type !=
	ACPI_STATE_C3
Date: Fri, 13 Apr 2012 11:06:17 +0200
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To: Jan Beulich <JBeulich@suse.com>
Cc: AndrePrzywara <andre.przywara@amd.com>, "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>, Keir Fraser <keir@xen.org>, Boris Ostrovsky <Boris.Ostrovsky@amd.com>, Wei Huang <wei.huang2@amd.com>, Yang Z Zhang <yang.z.zhang@intel.com>
List-Id: xen-devel@lists.xenproject.org

On 04/13/2012 10:30 AM, Jan Beulich wrote:
>>>> On 13.04.12 at 04:14, "Zhang, Yang Z"<yang.z.zhang@intel.com>  wrote:
>> This should not be enough. No need to check bm when going to C2.
>> How about the following patch:
>
> That looks right, but I'd prefer to simplify it a little:
>
> --- a/xen/arch/x86/acpi/cpu_idle.c
> +++ b/xen/arch/x86/acpi/cpu_idle.c
> @@ -493,7 +493,9 @@ static void acpi_processor_idle(void)
>            * not set. In that case we cannot do much, we enter C3
>            * without doing anything.
>            */
> -        if ( power->flags.bm_check&&  power->flags.bm_control )
> +        if ( cx->type != ACPI_STATE_C3 )
> +            /* nothing to be done here */;
> +        else if ( power->flags.bm_check&&  power->flags.bm_control )
>           {
>               spin_lock(&c3_cpu_status.lock);
>               if ( ++c3_cpu_status.count == num_online_cpus() )
> @@ -515,7 +517,8 @@ static void acpi_processor_idle(void)
>           /* Invoke C3 */
>           acpi_idle_do_entry(cx);
>
> -        if ( power->flags.bm_check&&  power->flags.bm_control )
> +        if ( (cx->type == ACPI_STATE_C3)&&
> +             power->flags.bm_check&&  power->flags.bm_control )
>           {
>               /* Enable bus master arbitration */
>               spin_lock(&c3_cpu_status.lock);
>
> Also, Yang, you didn't provide a S-o-b - are you okay with me adding
> it?
>
> If you're both okay with above patch, I'll see that I get it committed.
>
> Jan
>
>

This looks good to me. Thanks
Wei