From: Will Deacon <will.deacon@arm.com>
To: Doug Anderson <dianders@chromium.org>
Cc: "olof@lixom.net" <olof@lixom.net>,
Sonny Rao <sonnyrao@chromium.org>,
Catalin Marinas <Catalin.Marinas@arm.com>,
Mark Rutland <Mark.Rutland@arm.com>,
Stephen Boyd <sboyd@codeaurora.org>,
Marc Zyngier <Marc.Zyngier@arm.com>,
Sudeep Holla <Sudeep.Holla@arm.com>,
Christopher Covington <cov@codeaurora.org>,
Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
Nathan Lynch <Nathan_Lynch@mentor.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"robh+dt@kernel.org" <robh+dt@kernel.org>,
Pawel Moll <Pawel.Moll@arm.com>,
"ijc+devicetree@hellion.org.uk" <ijc+devicetree@hellion.org.uk>,
"galak@codeaurora.org" <galak@codeaurora.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] clocksource: arch_timer: Allow the device tree to specify the physical timer
Date: Thu, 11 Sep 2014 18:07:16 +0100 [thread overview]
Message-ID: <20140911170716.GA6158@arm.com> (raw)
In-Reply-To: <CAD=FV=WECbZ4L=-C+F9K6kfiPUi7ar3a4a7Upq2TqDYYPGoOrA@mail.gmail.com>
On Thu, Sep 11, 2014 at 05:59:53PM +0100, Doug Anderson wrote:
> On Thu, Sep 11, 2014 at 9:47 AM, Will Deacon <will.deacon@arm.com> wrote:
> > I'd say `Only supported for ARM' to better match what we've done. Probably
> > also worth mentioning that this relies on the hypervisor/firmware having set
> > CNTHCTL.PL1PCEN and CNTHCTL.EL1PCTEN (but assumedly made a mess of CNTVOFF
> > ;) if you want to boot on the non-secure side (e.g. as a guest).
>
> Note that the reset value of CNTHCTL.PL1PCEN and CNTHCTL.PL1PCTEN are
> both 1 in my version of the ARM ARM. On the other hand CNTVOFF is
> documented to have an UNKNOWN reset value. If only ARM had guaranteed
> that CNTVOFF started out as 0 (which seems like it would have been
> sensible) we wouldn't be in this mess. :-/
I'm afraid we went the opposite way -- in ARMv8 there are a tiny handful
of EL3 registers that are well-defined out of reset, then the rest of the
system is UNKNOWN. The hardware guys prefer that and it can also be useful
for very low-level debugging (system crashes, do a reset, read out the
state).
Will
next prev parent reply other threads:[~2014-09-11 17:07 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-11 16:16 [PATCH v2] clocksource: arch_timer: Allow the device tree to specify the physical timer Doug Anderson
[not found] ` <1410452204-7277-1-git-send-email-dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
2014-09-11 16:47 ` Will Deacon
[not found] ` <20140911164710.GW6158-5wv7dgnIgG8@public.gmane.org>
2014-09-11 16:59 ` Doug Anderson
2014-09-11 17:07 ` Will Deacon [this message]
2014-09-11 17:14 ` Doug Anderson
2014-09-11 17:00 ` Marc Zyngier
[not found] ` <5411D528.4050605-5wv7dgnIgG8@public.gmane.org>
2014-09-11 17:11 ` Doug Anderson
[not found] ` <CAD=FV=XMmizxJFPj0FEhJ7Gk4ZcQaUJDxf_Qq5kGKSvxDFVmzg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2014-09-11 17:22 ` Marc Zyngier
[not found] ` <5411DA67.2040402-5wv7dgnIgG8@public.gmane.org>
2014-09-11 17:29 ` Doug Anderson
[not found] ` <CAD=FV=UQfo4J3P4wGjOhQZQ5KXKgYAdjPsi1ykKZxQw-FwJz8w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2014-09-11 17:43 ` Marc Zyngier
[not found] ` <5411DF5D.8060906-5wv7dgnIgG8@public.gmane.org>
2014-09-11 23:55 ` Doug Anderson
2014-09-11 23:56 ` Stephen Boyd
[not found] ` <54123697.4070804-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
2014-09-12 0:01 ` Doug Anderson
2014-09-12 10:20 ` Marc Zyngier
2014-09-12 0:14 ` Sonny Rao
2014-09-12 1:17 ` Stephen Boyd
2014-09-12 3:25 ` Sonny Rao
2014-09-12 11:43 ` Christopher Covington
2014-09-12 12:14 ` Marc Zyngier
[not found] ` <5412E3BB.9030800-5wv7dgnIgG8@public.gmane.org>
2014-09-12 18:59 ` Stephen Boyd
[not found] ` <54134291.3040700-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
2014-09-15 11:10 ` Catalin Marinas
2014-09-15 20:33 ` Stephen Boyd
2014-09-15 21:47 ` Sonny Rao
2014-09-15 21:49 ` Stephen Boyd
2014-09-15 21:52 ` Sonny Rao
[not found] ` <CAPz6YkWbxiGHO8RK==HbQ3P22amZ9sDKpGew=a2U8gO7soQCDg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2014-09-15 22:04 ` Sonny Rao
2014-09-15 22:51 ` Christopher Covington
[not found] ` <54176D62.9010600-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
2014-09-16 0:24 ` Sonny Rao
2014-09-16 10:42 ` Catalin Marinas
[not found] ` <20140916104242.GC27273-5wv7dgnIgG8@public.gmane.org>
2014-09-16 11:22 ` Christopher Covington
[not found] ` <54174CFF.7050504-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
2014-09-16 11:03 ` Catalin Marinas
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20140911170716.GA6158@arm.com \
--to=will.deacon@arm.com \
--cc=Catalin.Marinas@arm.com \
--cc=Lorenzo.Pieralisi@arm.com \
--cc=Marc.Zyngier@arm.com \
--cc=Mark.Rutland@arm.com \
--cc=Nathan_Lynch@mentor.com \
--cc=Pawel.Moll@arm.com \
--cc=Sudeep.Holla@arm.com \
--cc=cov@codeaurora.org \
--cc=daniel.lezcano@linaro.org \
--cc=devicetree@vger.kernel.org \
--cc=dianders@chromium.org \
--cc=galak@codeaurora.org \
--cc=ijc+devicetree@hellion.org.uk \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=olof@lixom.net \
--cc=robh+dt@kernel.org \
--cc=sboyd@codeaurora.org \
--cc=sonnyrao@chromium.org \
--cc=tglx@linutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).