From mboxrd@z Thu Jan 1 00:00:00 1970 From: ccross@google.com (Colin Cross) Date: Fri, 22 Apr 2011 14:18:06 -0700 Subject: Common clock and dvfs In-Reply-To: <20110422203526.GC4768@sirena.org.uk> References: <20110422194027.GB4768@sirena.org.uk> <20110422203526.GC4768@sirena.org.uk> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, Apr 22, 2011 at 1:35 PM, Mark Brown wrote: > On Fri, Apr 22, 2011 at 12:48:37PM -0700, Colin Cross wrote: >> On Fri, Apr 22, 2011 at 12:40 PM, Mark Brown > >> > This sounds like it assumes a 1:1 mapping between clocks and supplies >> > which is going to break at some point. ?It should be handlable but will >> > add complexity. > >> Almost every platform requires a many-to-one mapping between clocks >> and supplies (many clocks fed off one supply), and I bet at least one >> platform has one clock that requires changing two supplies, so a > > In most of the platforms I've looked at the supported configurations are > specified en masse as operating points so it definitely ends up being > the case, you get a set of frequencies and a set of voltages specified > as a block. I see. Do you happen to know if there are any max voltage requirements for clocks? Would running one clock in a group at a low operating point and another at a high operating point cause a problem, assuming the voltage is set to what is required by the high operating point?