linux-kernel - Re: Ask help about pre_init_apic

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Message-ID: <1410444181.7023.25.camel@linux.intel.com>
Date:	Thu, 11 Sep 2014 17:03:01 +0300
From:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Jiang Liu <jiang.liu@...ux.intel.com>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	x86@...nel.org
Subject: Re: Ask help about pre_init_apic_IRQ0()

On Thu, 2014-09-11 at 14:58 +0200, Thomas Gleixner wrote:
[]

> According to the MID code the apbt horror is only used for moorestown.
> Medfield and later use the local apic timer without the apbt nonsense.
> 
> The best thing we can do is to drop moorestown support and get rid of
> that apbt nonsense alltogether.

Alan Cox removed Moorestown (as a platform) support in 2012 IIRC.
So, AFAIK you may safely remove those leftovers.

> I don't think anyone deeply cares about it not being supported from
> 3.18 on. The number of devices which sport a moorestown should be
> pretty limited and the only relevant use case of those is to act as a
> pocket heater with short battery life time. Its pretty pointless to
> update kernels on pocket heaters except for bragging reasons.
> 
> If someone at Intel really thinks that we need to keep moorestown
> alive for other than documentary and sentimental reasons, then we can
> move the apbt setup to x86_init.timers.setup_percpu_clockev(). At that
> point the IOAPIC is setup already, so it should just work. Untested
> patch below.

Suddenly I have one priority work to do and my Medfield tablet doesn't
boot by some reason. I would try to test it as soon as I can.

> 
> Thanks,
> 
> 	tglx
> 
> ------------------
> Index: linux/arch/x86/platform/intel-mid/intel-mid.c
> ===================================================================
> --- linux.orig/arch/x86/platform/intel-mid/intel-mid.c
> +++ linux/arch/x86/platform/intel-mid/intel-mid.c
> @@ -81,26 +81,34 @@ static unsigned long __init intel_mid_ca
>  	return 0;
>  }
>  
> +static void __init intel_mid_setup_bp_timer(void)
> +{
> +	apbt_time_init();
> +	setup_boot_APIC_clock();
> +}
> +
>  static void __init intel_mid_time_init(void)
>  {
>  	sfi_table_parse(SFI_SIG_MTMR, NULL, NULL, sfi_parse_mtmr);
> +
>  	switch (intel_mid_timer_options) {
>  	case INTEL_MID_TIMER_APBT_ONLY:
>  		break;
>  	case INTEL_MID_TIMER_LAPIC_APBT:
> -		x86_init.timers.setup_percpu_clockev = setup_boot_APIC_clock;
> +		/* Use apbt and local apic */
> +		x86_init.timers.setup_percpu_clockev = intel_mid_setup_bp_timer;
>  		x86_cpuinit.setup_percpu_clockev = setup_secondary_APIC_clock;
> -		break;
> +		return;
>  	default:
>  		if (!boot_cpu_has(X86_FEATURE_ARAT))
>  			break;
> +		/* Lapic only, no apbt */
>  		x86_init.timers.setup_percpu_clockev = setup_boot_APIC_clock;
>  		x86_cpuinit.setup_percpu_clockev = setup_secondary_APIC_clock;
>  		return;
>  	}
> -	/* we need at least one APB timer */
> -	pre_init_apic_IRQ0();
> -	apbt_time_init();
> +
> +	x86_init.timers.setup_percpu_clockev = apbt_time_init;
>  }
>  
>  static void intel_mid_arch_setup(void)


-- 
Andy Shevchenko <andriy.shevchenko@...el.com>
Intel Finland Oy

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