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From: Rob Herring <robherring2@gmail.com>
To: Afzal Mohammed <afzal@ti.com>
Cc: linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	devicetree-discuss@lists.ozlabs.org, linux-doc@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Russell King <linux@arm.linux.org.uk>,
	Nicolas Pitre <nico@linaro.org>, Sekhar Nori <nsekhar@ti.com>,
	Will Deacon <will.deacon@arm.com>,
	Rob Herring <rob.herring@calxeda.com>,
	Santosh Shilimkar <santosh.shilimkar@ti.com>,
	Syed Mohammed Khasim <khasim@ti.com>
Subject: Re: [RFC 2/8] ARM: twd: register clock event for 1 core SMP
Date: Mon, 18 Feb 2013 07:47:29 -0600	[thread overview]
Message-ID: <512230F1.8020208@gmail.com> (raw)
In-Reply-To: <a7f62b8580aa4b33d5658f4f03371a453adaea9b.1361166003.git.afzal@ti.com>

On 02/18/2013 12:30 AM, Afzal Mohammed wrote:
> Register percpu local timer for scheduler tick in the case of one core
> SMP configuration. In other cases - secondary cpu's as well as boot
> cpu's having more than one core, this is being registered as per
> existing boot flow, with a difference that they happens after delay
> calibration. Registering the clock for tick in case of one core should
> be done before Kernel calibrates delay (this is required to boot,
> unless local timer is the only one registered for tick). Registering
> twd local timer at init_time (which platforms are doing now) helps
> achieve that with the proposed change.
> 
> This helps in an almost booting Kernel (minimal) by only relying on
> ARM parts for an A9 one core SMP.
> 
> Signed-off-by: Afzal Mohammed <afzal@ti.com>
> ---
>  arch/arm/kernel/smp_twd.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c
> index 616268c..118f4f2 100644
> --- a/arch/arm/kernel/smp_twd.c
> +++ b/arch/arm/kernel/smp_twd.c
> @@ -335,6 +335,9 @@ static int __init twd_local_timer_common_register(struct device_node *np)
>  
>  	twd_get_clock(np);
>  
> +	if (num_possible_cpus() == 1)
> +		twd_timer_setup(evt);
> +

Shouldn't this be fixed in the core code, so the same issue is fixed for
all timers?

Rob

>  	return 0;
>  
>  out_irq:
> 


WARNING: multiple messages have this Message-ID (diff)
From: Rob Herring <robherring2-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: Afzal Mohammed <afzal-l0cyMroinI0@public.gmane.org>
Cc: Russell King <linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>,
	linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>,
	devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org,
	Nicolas Pitre <nico-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
	Sekhar Nori <nsekhar-l0cyMroinI0@public.gmane.org>,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Rob Herring <rob.herring-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org>,
	Santosh Shilimkar
	<santosh.shilimkar-l0cyMroinI0@public.gmane.org>,
	Syed Mohammed Khasim <khasim-l0cyMroinI0@public.gmane.org>,
	linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
Subject: Re: [RFC 2/8] ARM: twd: register clock event for 1 core SMP
Date: Mon, 18 Feb 2013 07:47:29 -0600	[thread overview]
Message-ID: <512230F1.8020208@gmail.com> (raw)
In-Reply-To: <a7f62b8580aa4b33d5658f4f03371a453adaea9b.1361166003.git.afzal-l0cyMroinI0@public.gmane.org>

On 02/18/2013 12:30 AM, Afzal Mohammed wrote:
> Register percpu local timer for scheduler tick in the case of one core
> SMP configuration. In other cases - secondary cpu's as well as boot
> cpu's having more than one core, this is being registered as per
> existing boot flow, with a difference that they happens after delay
> calibration. Registering the clock for tick in case of one core should
> be done before Kernel calibrates delay (this is required to boot,
> unless local timer is the only one registered for tick). Registering
> twd local timer at init_time (which platforms are doing now) helps
> achieve that with the proposed change.
> 
> This helps in an almost booting Kernel (minimal) by only relying on
> ARM parts for an A9 one core SMP.
> 
> Signed-off-by: Afzal Mohammed <afzal-l0cyMroinI0@public.gmane.org>
> ---
>  arch/arm/kernel/smp_twd.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c
> index 616268c..118f4f2 100644
> --- a/arch/arm/kernel/smp_twd.c
> +++ b/arch/arm/kernel/smp_twd.c
> @@ -335,6 +335,9 @@ static int __init twd_local_timer_common_register(struct device_node *np)
>  
>  	twd_get_clock(np);
>  
> +	if (num_possible_cpus() == 1)
> +		twd_timer_setup(evt);
> +

Shouldn't this be fixed in the core code, so the same issue is fixed for
all timers?

Rob

>  	return 0;
>  
>  out_irq:
> 

WARNING: multiple messages have this Message-ID (diff)
From: robherring2@gmail.com (Rob Herring)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC 2/8] ARM: twd: register clock event for 1 core SMP
Date: Mon, 18 Feb 2013 07:47:29 -0600	[thread overview]
Message-ID: <512230F1.8020208@gmail.com> (raw)
In-Reply-To: <a7f62b8580aa4b33d5658f4f03371a453adaea9b.1361166003.git.afzal@ti.com>

On 02/18/2013 12:30 AM, Afzal Mohammed wrote:
> Register percpu local timer for scheduler tick in the case of one core
> SMP configuration. In other cases - secondary cpu's as well as boot
> cpu's having more than one core, this is being registered as per
> existing boot flow, with a difference that they happens after delay
> calibration. Registering the clock for tick in case of one core should
> be done before Kernel calibrates delay (this is required to boot,
> unless local timer is the only one registered for tick). Registering
> twd local timer at init_time (which platforms are doing now) helps
> achieve that with the proposed change.
> 
> This helps in an almost booting Kernel (minimal) by only relying on
> ARM parts for an A9 one core SMP.
> 
> Signed-off-by: Afzal Mohammed <afzal@ti.com>
> ---
>  arch/arm/kernel/smp_twd.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c
> index 616268c..118f4f2 100644
> --- a/arch/arm/kernel/smp_twd.c
> +++ b/arch/arm/kernel/smp_twd.c
> @@ -335,6 +335,9 @@ static int __init twd_local_timer_common_register(struct device_node *np)
>  
>  	twd_get_clock(np);
>  
> +	if (num_possible_cpus() == 1)
> +		twd_timer_setup(evt);
> +

Shouldn't this be fixed in the core code, so the same issue is fixed for
all timers?

Rob

>  	return 0;
>  
>  out_irq:
> 

  reply	other threads:[~2013-02-18 13:47 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-02-18  6:28 [RFC 0/8] ARM: AM43 (OMAP2+) boot support Afzal Mohammed
2013-02-18  6:28 ` Afzal Mohammed
2013-02-18  6:28 ` Afzal Mohammed
2013-02-18  6:30 ` [RFC 1/8] ARM: localtimer: return percpu clkevt on register Afzal Mohammed
2013-02-18  6:30   ` Afzal Mohammed
2013-02-18  6:30 ` [RFC 2/8] ARM: twd: register clock event for 1 core SMP Afzal Mohammed
2013-02-18  6:30   ` Afzal Mohammed
2013-02-18 13:47   ` Rob Herring [this message]
2013-02-18 13:47     ` Rob Herring
2013-02-18 13:47     ` Rob Herring
2013-02-19  8:00     ` Mohammed, Afzal
2013-02-19  8:00       ` Mohammed, Afzal
2013-02-19  8:00       ` Mohammed, Afzal
2013-02-18  6:30 ` [RFC 3/8] ARM: twd: clock rate from DT (if no DT clk tree) Afzal Mohammed
2013-02-18  6:30   ` Afzal Mohammed
2013-02-18  6:30 ` [RFC 4/8] ARM: am33xx: ll debug config help Afzal Mohammed
2013-02-18  6:30   ` Afzal Mohammed
2013-02-18  6:30 ` [RFC 5/8] ARM: OMAP2+: am43: Kconfig Afzal Mohammed
2013-02-18  6:30   ` Afzal Mohammed
2013-02-18  6:30 ` [RFC 6/8] ARM: OMAP2+: am43: basic dt support Afzal Mohammed
2013-02-18  6:30   ` Afzal Mohammed
2013-02-18  6:30 ` [RFC 7/8] ARM: dts: am4372: initial support Afzal Mohammed
2013-02-18  6:30   ` Afzal Mohammed
2013-02-18  6:30 ` [RFC 8/8] ARM: dts: am43-pre-silicon support Afzal Mohammed
2013-02-18  6:30   ` Afzal Mohammed

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