From: Stephen Boyd <sboyd@codeaurora.org>
To: Mason <mpeg.blue@free.fr>, Stefan Agner <stefan@agner.ch>
Cc: Mark Rutland <mark.rutland@arm.com>,
Linux PM <linux-pm@vger.kernel.org>,
Rob Herring <rob.herring@calxeda.com>,
cpufreq <cpufreq@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: Delays, clocks, timers, hrtimers, etc
Date: Mon, 09 Feb 2015 11:01:10 -0800 [thread overview]
Message-ID: <54D903F6.3050608@codeaurora.org> (raw)
In-Reply-To: <54D576B1.4000001@free.fr>
On 02/06/15 18:21, Mason wrote:
>
>
> config HAVE_ARM_TWD
> bool
> depends on SMP
> select CLKSRC_OF if OF
> help
> This options enables support for the ARM timer and watchdog unit
>
> One problem I see is that HAVE_ARM_TWD depends on SMP...
>
> One of the systems I want to support is UP (single-core Cortex A9).
> Does that mean I should use an SMP kernel even for that system?
> Or is there a different subsystem for UP systems?
I don't see any problem with the TWD dropping the dependency on SMP. The
code should work the same on a UP configuration and if that's the only
timer you have that can deliver interrupts to your processor then it
would be required. You'd still need a clocksource though, which the TWD
doesn't provide.
--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project
WARNING: multiple messages have this Message-ID (diff)
From: sboyd@codeaurora.org (Stephen Boyd)
To: linux-arm-kernel@lists.infradead.org
Subject: Delays, clocks, timers, hrtimers, etc
Date: Mon, 09 Feb 2015 11:01:10 -0800 [thread overview]
Message-ID: <54D903F6.3050608@codeaurora.org> (raw)
In-Reply-To: <54D576B1.4000001@free.fr>
On 02/06/15 18:21, Mason wrote:
>
>
> config HAVE_ARM_TWD
> bool
> depends on SMP
> select CLKSRC_OF if OF
> help
> This options enables support for the ARM timer and watchdog unit
>
> One problem I see is that HAVE_ARM_TWD depends on SMP...
>
> One of the systems I want to support is UP (single-core Cortex A9).
> Does that mean I should use an SMP kernel even for that system?
> Or is there a different subsystem for UP systems?
I don't see any problem with the TWD dropping the dependency on SMP. The
code should work the same on a UP configuration and if that's the only
timer you have that can deliver interrupts to your processor then it
would be required. You'd still need a clocksource though, which the TWD
doesn't provide.
--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project
next prev parent reply other threads:[~2015-02-09 19:01 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-28 13:16 Delays, clocks, timers, hrtimers, etc Mason
2015-01-28 13:16 ` Mason
2015-01-29 13:57 ` Mason
2015-01-29 13:57 ` Mason
2015-02-03 12:09 ` Russell King - ARM Linux
2015-02-03 12:09 ` Russell King - ARM Linux
2015-02-06 18:37 ` Mason
2015-02-06 18:37 ` Mason
2015-02-06 19:14 ` Russell King - ARM Linux
2015-02-06 19:14 ` Russell King - ARM Linux
2015-02-06 21:03 ` Mason
2015-02-06 21:03 ` Mason
2015-02-07 10:42 ` Russell King - ARM Linux
2015-02-07 10:42 ` Russell King - ARM Linux
2015-02-09 7:45 ` Michal Simek
2015-02-09 7:45 ` Michal Simek
2015-02-09 16:10 ` Sören Brinkmann
2015-02-09 16:10 ` Sören Brinkmann
2015-02-09 23:27 ` Mason
2015-02-09 23:27 ` Mason
2015-02-06 20:25 ` Stefan Agner
2015-02-06 20:25 ` Stefan Agner
2015-02-06 21:17 ` Mason
2015-02-06 21:17 ` Mason
2015-02-06 21:31 ` Stefan Agner
2015-02-06 21:31 ` Stefan Agner
2015-02-07 2:21 ` Mason
2015-02-07 2:21 ` Mason
2015-02-07 9:51 ` Russell King - ARM Linux
2015-02-07 9:51 ` Russell King - ARM Linux
2015-02-09 19:01 ` Stephen Boyd [this message]
2015-02-09 19:01 ` Stephen Boyd
2015-02-09 22:31 ` Mason
2015-02-09 22:31 ` Mason
2015-02-09 23:17 ` Stephen Boyd
2015-02-09 23:17 ` Stephen Boyd
2015-02-09 23:50 ` Mason
2015-02-09 23:50 ` Mason
2015-02-11 17:43 ` Mason
2015-02-11 17:43 ` Mason
2015-02-11 18:45 ` Stephen Boyd
2015-02-11 18:45 ` Stephen Boyd
2015-02-11 21:58 ` Mason
2015-02-11 21:58 ` Mason
2015-02-11 23:26 ` Stephen Boyd
2015-02-11 23:26 ` Stephen Boyd
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