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From: Will Deacon <will@kernel.org>
To: Xin Hao <xhao@linux.alibaba.com>
Cc: fweisbec@gmail.com, john.stultz@linaro.org,
	kernel-team@android.com, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, lorenzo@google.com, maz@kernel.org,
	mika.penttila@nextfour.com, sboyd@kernel.org, tglx@linutronix.de
Subject: Re: [PATCH v2 2/5] tick/broadcast: Split __tick_broadcast_oneshot_control() into a helper
Date: Thu, 27 May 2021 12:55:30 +0100	[thread overview]
Message-ID: <20210527115530.GC22019@willie-the-truck> (raw)
In-Reply-To: <e0f6523f-36f8-188c-da99-4dcb51375522@linux.alibaba.com>

On Thu, May 27, 2021 at 07:35:03PM +0800, Xin Hao wrote:
> 
> 在 2021/5/27 下午4:22, Will Deacon 写道:
> > On Thu, May 27, 2021 at 03:23:06PM +0800, Xin Hao wrote:
> > >       I  had backport you  tick/broadcast: Prefer per-cpu relatives patches,
> > > 
> > > but i did not get the true result,  the Wakeup Devices are all null, why?
> > Probably because you don't have any suitable per-cpu timers to act as a
> > wakeup. Do you have a per-cpu timer registered with CLOCK_EVT_FEAT_PERCPU
> 
> Yes, you are right, but i want to know why the timer do not support 
> CLOCK_EVT_FEAT_PERCPU.

I suspect there may be drivers with the feature missing simply because it
wasn't really used for much until now (I think it just prevented use for
broadcast). However, before adding that to a timer, you do need to make
sure that it really is banked per-cpu (or at least handles racing accesses)
as well as having the per-cpu irq.

Will

  reply	other threads:[~2021-05-27 11:55 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-24 22:18 [PATCH v2 0/5] tick/broadcast: Allow per-cpu timers to be used instead of broadcast Will Deacon
2021-05-24 22:18 ` [PATCH v2 1/5] tick/broadcast: Drop unneeded CONFIG_GENERIC_CLOCKEVENTS_BROADCAST guard Will Deacon
2021-05-31 15:07   ` [tip: timers/core] " tip-bot2 for Will Deacon
2021-05-24 22:18 ` [PATCH v2 2/5] tick/broadcast: Split __tick_broadcast_oneshot_control() into a helper Will Deacon
2021-05-27  7:23   ` Xin Hao
2021-05-27  8:22     ` Will Deacon
2021-05-27 11:35       ` Xin Hao
2021-05-27 11:55         ` Will Deacon [this message]
2021-05-27 11:56         ` Will Deacon
2021-05-31 14:29           ` Thomas Gleixner
2021-06-01 12:13             ` Will Deacon
2021-06-01 18:14               ` Thomas Gleixner
2021-05-31 15:06   ` [tip: timers/core] " tip-bot2 for Will Deacon
2021-05-24 22:18 ` [PATCH v2 3/5] tick/broadcast: Prefer per-cpu oneshot wakeup timers to broadcast Will Deacon
2021-05-31 15:06   ` [tip: timers/core] " tip-bot2 for Will Deacon
2021-05-24 22:18 ` [PATCH v2 4/5] tick/broadcast: Program wakeup timer when entering idle if required Will Deacon
2021-05-31 15:06   ` [tip: timers/core] " tip-bot2 for Will Deacon
2021-05-24 22:18 ` [PATCH v2 5/5] timer_list: Print name of per-cpu wakeup device Will Deacon
2021-05-31 15:06   ` [tip: timers/core] " tip-bot2 for Will Deacon

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