From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Lezcano Subject: Re: [PATCH RFC 2/2] Documentation: arm: define DT C-states bindings Date: Tue, 03 Dec 2013 12:52:36 +0100 Message-ID: <529DC604.4050600@linaro.org> References: <1386001205-11978-1-git-send-email-lorenzo.pieralisi@arm.com> <1386001205-11978-3-git-send-email-lorenzo.pieralisi@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <1386001205-11978-3-git-send-email-lorenzo.pieralisi-5wv7dgnIgG8@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Lorenzo Pieralisi , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-pm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Dave Martin , Mark Rutland , Sudeep KarkadaNagesha , Charles Garcia Tobin , Nicolas Pitre , Rob Herring , Peter De Schrijver , Grant Likely , Santosh Shilimkar , Mark Hambleton , Hanjun Guo , Amit Kucheria , Vincent Guittot List-Id: devicetree@vger.kernel.org On 12/02/2013 05:20 PM, Lorenzo Pieralisi wrote: > ARM based platforms implement a variety of power management schemes t= hat > allow processors to enter at run-time low-power states, aka C-states > in ACPI jargon. The parameters defining these C-states vary on a per-= platform > basis forcing the OS to hardcode the state parameters in platform > specific static tables whose size grows as the number of platforms su= pported > in the kernel increases and hampers device drivers standardization. > > Therefore, this patch aims at standardizing C-state device tree bindi= ngs for > ARM platforms. Bindings define C-state parameters inclusive of entry = methods > and state latencies, to allow operating systems to retrieve the > configuration entries from the device tree and initialize the related > power management drivers, paving the way for common code in the kerne= l > to deal with power states and removing the need for static data in cu= rrent > and previous kernel versions. > > Signed-off-by: Lorenzo Pieralisi Hi Lorenzo, thanks for the detailed description. Just a couple of typos below. [ ... ] > +- cpu-power-states node > + > + Usage: Optional - On ARM systems, is a container of processor C-sta= te > + nodes. If the system does not provide CPU power > + management capabilities or the processor just > + supports WFI (C1 state) a cpu-power-states node is > + not required. > + > + Description: cpu-power-states node is a container node, where its > + subnodes describe the CPU low-power C-states. > + > + Node name must be "cpu-power-states". > + > + The cpu-power-states node's parent node must be cpus node. > + > + The cpu-power-states node's child nodes can be: > + > + - one or more state nodes > + > + The cpu-power-states node must contain the following properties: > + > + - compatible > + Value type: > + Usage: Required Invert the field above to be consistent with the definitions below. [ ... ] > + - power-depth > + Usage: Required > + Value type: > + Definition: Integer value, starting from 2 (value 0 meaning > + running and value 1 representing power depth of > + wfi (C1)), that defines the level of depth of a > + power state. > + The system denotes power states with different > + depths, an increasing value meaning less power > + consumption and might involve powering down more > + components. Devices that are affected by ^^^ extra space [ ... ] Thanks -- Daniel --=20 Linaro.org =E2=94=82 Open source software fo= r ARM SoCs =46ollow Linaro: Facebook | Twitter | Blog -- To unsubscribe from this list: send the line "unsubscribe devicetree" i= n the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html