From: Maxime Ripard <maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
To: Julian Calaby <julian.calaby-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: public_timo.s-fWgRPtSzPNU3WX+qO2AYSQ@public.gmane.org,
Rob Herring <robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
Pawel Moll <pawel.moll-5wv7dgnIgG8@public.gmane.org>,
Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org>,
Ian Campbell
<ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org>,
Kumar Gala <galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>,
Russell King <linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>,
devicetree <devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
"Mailing List,
Arm"
<linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org>,
"linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
linux-sunxi <linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org>,
Chen-Yu Tsai <wens-jdAy2FN1RRM@public.gmane.org>
Subject: Re: [PATCH] ARM: dts: sunxi: Raise minimum CPU voltage for sun7i-a20 to a level all boards can supply
Date: Mon, 3 Aug 2015 11:16:24 +0200 [thread overview]
Message-ID: <20150803091624.GZ2564@lukather> (raw)
In-Reply-To: <CAGRGNgV6b9yt2HnB2x2Wyc05KEahoX-Y+mVhxsryztcfA36H1g-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
[-- Attachment #1: Type: text/plain, Size: 1038 bytes --]
On Mon, Aug 03, 2015 at 09:35:51AM +1000, Julian Calaby wrote:
> Hi Timo,
>
> On Mon, Aug 3, 2015 at 5:23 AM, Timo Sigurdsson
> <public_timo.s-fWgRPtSzPNU3WX+qO2AYSQ@public.gmane.org> wrote:
> > sun7i-a20.dtsi contains an cpufreq operating point at 0.9 volts. Most A20 boards
> > (or all?), however, do not allow the voltage to go below 1.0V. Thus, raise the
> > voltage for the lowest operating point to 1.0V so all boards can actually use
> > it.
>
> Surely it wouldn't be added here if some could supply 0.9v.
>
> Is the code that uses this smart enough to sensibly switch between two
> operating points with the same frequency and different voltages? If
> so, maybe just add a 144MHz @ 1.0v operating point?
And how would it choose between the two exactly ? Switch to the 144MHz
@ 0.9V and see if it works ? If it doesn't you might have screwed your
system already, and might not be able to recover from it at all.
Maxime
--
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
next prev parent reply other threads:[~2015-08-03 9:16 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-02 19:23 [PATCH] ARM: dts: sunxi: Raise minimum CPU voltage for sun7i-a20 to a level all boards can supply Timo Sigurdsson
[not found] ` <1438543386-7253-1-git-send-email-public_timo.s-fWgRPtSzPNU3WX+qO2AYSQ@public.gmane.org>
2015-08-02 23:35 ` [linux-sunxi] " Julian Calaby
[not found] ` <CAGRGNgV6b9yt2HnB2x2Wyc05KEahoX-Y+mVhxsryztcfA36H1g-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-08-03 2:37 ` Chen-Yu Tsai
[not found] ` <CAGb2v67o-=_cL2RWfXJ+3C86zfQ_1b5DYRi3_zwvwy6su6+gdw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-08-03 4:22 ` Julian Calaby
[not found] ` <CAGRGNgXH90m9h0DDejd5MTf8enduGFQ8dPKrRhmc8Z6y_PaC1w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-08-03 4:26 ` Chen-Yu Tsai
2015-08-03 9:03 ` Timo Sigurdsson
[not found] ` <20150803090352.621CC6C80865-RzmsueL7+k6AvxNu/8lEInnhMCiq3JZZ@public.gmane.org>
2015-08-03 9:34 ` Maxime Ripard
2015-08-03 9:36 ` [linux-sunxi] " Julian Calaby
2015-08-04 8:51 ` Timo Sigurdsson
2015-08-03 9:28 ` Maxime Ripard
2015-08-03 8:37 ` Timo Sigurdsson
[not found] ` <20150803083751.1BCF56C80391-RzmsueL7+k6AvxNu/8lEInnhMCiq3JZZ@public.gmane.org>
2015-08-03 9:23 ` Maxime Ripard
2015-08-03 9:16 ` Maxime Ripard [this message]
2015-08-03 9:13 ` Maxime Ripard
2015-08-04 8:38 ` Timo Sigurdsson
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