linux-kernel - Re: [PATCH v3 0/5] clocksource: sun5i: Support parent clock rate changes

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Message-ID: <20150319225344.GF4255@lukather>
Date:	Thu, 19 Mar 2015 23:53:44 +0100
From:	Maxime Ripard <maxime.ripard@...e-electrons.com>
To:	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>
Cc:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3 0/5] clocksource: sun5i: Support parent clock rate
 changes

Hi Daniel,

On Thu, Mar 05, 2015 at 11:20:51AM +0100, Maxime Ripard wrote:
> Hi,
> 
> The Allwinner HS timers have the AHB clock as their parent
> clock. Since this clock is shared with other devices, we could very
> well have another driver requesting a rate change of that clock,
> making our timer change frequency at the same time.
> 
> This is especially true on the A31, where the DMA controller needs to
> do such a rate change, making the HS timer unreliable at the time on
> the A31.
> 
> This serie makes some cleanups and implements clock notifiers to be
> able to reflect such rate changes and make sure that the timer is
> always working.
> 
> Maxime
> 
> Changes from v2:
>   - Rebased on top of v4.0-rc1
>   - Removed the local_irq_save/restore around clockevents_update_freq
> 
> Changes from v1:
>   - Changed the interrupt name to its previous value
> 
> Maxime Ripard (5):
>   clocksource: sun5i: Switch to request_irq
>   clocksource: sun5i: Use of_io_request_and_map
>   clocksource: sun5i: Remove sched_clock
>   clocksource: sun5i: Refactor the current code
>   clocksource: sun5i: Add clock notifiers

Have these patches been merged?

If not, it woulde be great if the third one ("clocksource: sun5i:
Remove sched_clock") was merged for 4.0.

The sched_clock we use on some system is this timer's, and since we
started using cpufreq, the cpu clock (that is one of the timer's clock
indirect parent) now changes, along with the actual sched_clock rate.

We can safely remove the sched_clock on those systems, since we have
other reliable sched_clock in the system.

Thanks,
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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