From: Daniel Lezcano <daniel.lezcano-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
To: Marc Zyngier <marc.zyngier-5wv7dgnIgG8@public.gmane.org>,
Brian Norris
<briannorris-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>,
Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
Cc: Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org>,
linux-rockchip-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
Stephen Boyd <sboyd-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
Subject: Re: [PATCH] clocksource: arm_arch_timer: Don't assume clock runs in suspend
Date: Fri, 16 Sep 2016 10:10:33 +0200 [thread overview]
Message-ID: <dacd2461-8989-323d-d2ad-b20d10c9282b@linaro.org> (raw)
In-Reply-To: <57DBA81F.2060404-5wv7dgnIgG8@public.gmane.org>
On 16/09/2016 10:06, Marc Zyngier wrote:
> Hi Brian,
>
> On 16/09/16 06:49, Brian Norris wrote:
>> Since commit 4fbcdc813fb9 ("clocksource: arm_arch_timer: Use clocksource
>> for suspend timekeeping"), this driver assumes that the ARM architected
>> timer keeps running in suspend. This is not the case for some ARM SoCs,
>> depending on the HW state used for system suspend. Let's not assume that
>> all SoCs support this, and instead only support this if the device tree
>> explicitly tells us it's "always on". In all other cases, just fall back
>> to the RTC. This should be relatively harmless.
>
> I'm afraid you're confusing two things:
> - the counter, which *must* carry on counting no matter what, as
> (quoting the ARM ARM) "The system counter must be implemented in an
> always-on power domain"
> - the timer, which is allowed to be powered off, and can be tagged with
> the "always-on" property to indicate that it is guaranteed to stay up
> (which in practice only exists in virtual machines and never on real HW).
>
> If your counter does stop counting when suspended, then this is starting
> to either feel like a HW bug, or someone is killing the clock that feeds
> this counter when entering suspend.
>
> If this is the former, then we need a separate quirk to indicate the
> non-standard behaviour. If it is the latter, don't do it! ;-)
+1
-- Daniel
<http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs
Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook |
<http://twitter.com/#!/linaroorg> Twitter |
<http://www.linaro.org/linaro-blog/> Blog
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WARNING: multiple messages have this Message-ID (diff)
From: daniel.lezcano@linaro.org (Daniel Lezcano)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] clocksource: arm_arch_timer: Don't assume clock runs in suspend
Date: Fri, 16 Sep 2016 10:10:33 +0200 [thread overview]
Message-ID: <dacd2461-8989-323d-d2ad-b20d10c9282b@linaro.org> (raw)
In-Reply-To: <57DBA81F.2060404@arm.com>
On 16/09/2016 10:06, Marc Zyngier wrote:
> Hi Brian,
>
> On 16/09/16 06:49, Brian Norris wrote:
>> Since commit 4fbcdc813fb9 ("clocksource: arm_arch_timer: Use clocksource
>> for suspend timekeeping"), this driver assumes that the ARM architected
>> timer keeps running in suspend. This is not the case for some ARM SoCs,
>> depending on the HW state used for system suspend. Let's not assume that
>> all SoCs support this, and instead only support this if the device tree
>> explicitly tells us it's "always on". In all other cases, just fall back
>> to the RTC. This should be relatively harmless.
>
> I'm afraid you're confusing two things:
> - the counter, which *must* carry on counting no matter what, as
> (quoting the ARM ARM) "The system counter must be implemented in an
> always-on power domain"
> - the timer, which is allowed to be powered off, and can be tagged with
> the "always-on" property to indicate that it is guaranteed to stay up
> (which in practice only exists in virtual machines and never on real HW).
>
> If your counter does stop counting when suspended, then this is starting
> to either feel like a HW bug, or someone is killing the clock that feeds
> this counter when entering suspend.
>
> If this is the former, then we need a separate quirk to indicate the
> non-standard behaviour. If it is the latter, don't do it! ;-)
+1
-- Daniel
<http://www.linaro.org/> Linaro.org ? Open source software for ARM SoCs
Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook |
<http://twitter.com/#!/linaroorg> Twitter |
<http://www.linaro.org/linaro-blog/> Blog
next prev parent reply other threads:[~2016-09-16 8:10 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-16 5:49 [PATCH] clocksource: arm_arch_timer: Don't assume clock runs in suspend Brian Norris
2016-09-16 5:49 ` Brian Norris
2016-09-16 5:49 ` Brian Norris
2016-09-16 8:06 ` Marc Zyngier
2016-09-16 8:06 ` Marc Zyngier
[not found] ` <57DBA81F.2060404-5wv7dgnIgG8@public.gmane.org>
2016-09-16 8:10 ` Daniel Lezcano [this message]
2016-09-16 8:10 ` Daniel Lezcano
2016-09-19 23:14 ` Brian Norris
2016-09-19 23:14 ` Brian Norris
2016-09-20 7:47 ` Marc Zyngier
2016-09-20 7:47 ` Marc Zyngier
2016-09-28 1:23 ` Brian Norris
2016-09-28 1:23 ` Brian Norris
2016-09-29 16:08 ` Marc Zyngier
2016-09-29 16:08 ` Marc Zyngier
2016-10-04 17:49 ` Brian Norris
2016-10-04 17:49 ` Brian Norris
2016-10-19 1:24 ` Stephen Boyd
2016-10-19 1:24 ` Stephen Boyd
2016-10-19 1:36 ` Brian Norris
2016-10-19 1:36 ` Brian Norris
2016-10-19 1:36 ` Brian Norris
2016-10-19 1:55 ` Stephen Boyd
2016-10-19 1:55 ` Stephen Boyd
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