Re: [PATCH RT 11/20] ARM: imx: always use TWD on IMX6Q

From	Grygorii Strashko <grygorii.strashko@ti.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH RT 11/20] ARM: imx: always use TWD on IMX6Q
Date	2016-07-18 20:20 +0200
Message-ID	<rWlj4-1gf-57@gated-at.bofh.it> (permalink)
References	<rU6Rb-66R-3@gated-at.bofh.it> <rU6Rc-66R-43@gated-at.bofh.it> <rUcae-1jn-25@gated-at.bofh.it>
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On 07/12/2016 11:04 PM, Sebastian Andrzej Siewior wrote:
> * Steven Rostedt | 2016-07-12 10:24:16 [-0400]:
> 
>> 4.1.27-rt31-rc1 stable review patch.
>> If anyone has any objections, please let me know.
> 
> I don't recommend to cherry-pick this. The symbol it selects
> (HAVE_ARM_TWD) has "depends on SMP" in v4.1. In v4.4 there should be
> AM43xx which is UP and also uses the TWD so the change is simple here.
> 

yes. AM43xx is UP and supports ARM TWD, but there could be some 'issues' in !RT case :(

ARM TWD might be powered off in deep CPU Idle states and lose its context if !RT & CPUIDLE,
so there are should be backup broadcast timer configured. And that can cause build issues
related to tick_broadcast()->smp_cross_call().

I've solved it locally for OMAP2 only: commit 0b3e6fca4d1af4aa150d32506220f4241323a00c

^Just FYI. But may be it can be done in more generic way.

regards,
-grygorii

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[PATCH RT 11/20] ARM: imx: always use TWD on IMX6Q Steven Rostedt <rostedt@goodmis.org> - 2016-07-12 16:30 +0200
  Re: [PATCH RT 11/20] ARM: imx: always use TWD on IMX6Q Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-07-12 22:10 +0200
    Re: [PATCH RT 11/20] ARM: imx: always use TWD on IMX6Q Steven Rostedt <rostedt@goodmis.org> - 2016-07-12 22:30 +0200
    Re: [PATCH RT 11/20] ARM: imx: always use TWD on IMX6Q Grygorii Strashko <grygorii.strashko@ti.com> - 2016-07-18 20:20 +0200

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