From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Timo Sigurdsson" 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 10:37:51 +0200 (CEST) Message-ID: <20150803083751.1BCF56C80391@dd34104.kasserver.com> References: <1438543386-7253-1-git-send-email-public_timo.s@silentcreek.de> Reply-To: public_timo.s-fWgRPtSzPNU3WX+qO2AYSQ@public.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: In-Reply-To: List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , To: julian.calaby-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org Cc: robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, pawel.moll-5wv7dgnIgG8@public.gmane.org, mark.rutland-5wv7dgnIgG8@public.gmane.org, ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org, galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org, linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org, maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org, wens-jdAy2FN1RRM@public.gmane.org List-Id: devicetree@vger.kernel.org Hi Julian, Julian Calaby schrieb am 03.08.2015 01:35: >> 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. Maybe. I just know some boards don't (e.g. Cubieboard 2, Cubietruck, BananaPi) and don't know of any that does. But that's not my point. I think that a common minimum operating point, defined on the SOC level, should be defined in a way that works on all boards. > > 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? I never tried and I probably won't have time to test that before the weekend. The current behaviour is this, though: On boards that set their minimum CPU voltage to 1.0V, the lowest operating point will simply not be available to the user. > (Alternatively, would it make sense to modify the code that uses this > to use frequencies with voltages specified that are lower than can be > supplied with the lowest voltage it can?) Considering OPPv2 is in the works, maybe not? Thanks, Timo