Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932667AbcDLIRd (ORCPT ); Tue, 12 Apr 2016 04:17:33 -0400 Received: from mailout2.w1.samsung.com ([210.118.77.12]:29317 "EHLO mailout2.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932450AbcDLIR2 (ORCPT ); Tue, 12 Apr 2016 04:17:28 -0400 X-AuditID: cbfec7f5-f792a6d000001302-2f-570ca50cf3b4 Subject: Re: [PATCH v9 07/20] PM / devfreq: exynos: Update documentation for bus devices using passive governor To: Chanwoo Choi , myungjoo.ham@samsung.com, kyungmin.park@samsung.com, kgene@kernel.org, s.nawrocki@samsung.com, tomasz.figa@gmail.com References: <1460347078-15175-1-git-send-email-cw00.choi@samsung.com> <1460347078-15175-8-git-send-email-cw00.choi@samsung.com> Cc: rjw@rjwysocki.net, robh+dt@kernel.org, pawel.moll@arm.com, mark.rutland@arm.com, ijc+devicetree@hellion.org.uk, galak@codeaurora.org, linux@arm.linux.org.uk, linux.amoon@gmail.com, m.reichl@fivetechno.de, tjakobi@math.uni-bielefeld.de, inki.dae@samsung.com, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, linux-samsung-soc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org From: Krzysztof Kozlowski Message-id: <570CA50A.3010505@samsung.com> Date: Tue, 12 Apr 2016 09:34:34 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-version: 1.0 In-reply-to: <1460347078-15175-8-git-send-email-cw00.choi@samsung.com> Content-type: text/plain; charset=windows-1252 Content-transfer-encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrFIsWRmVeSWpSXmKPExsVy+t/xa7o8S3nCDdqeMFlc//Kc1WL+kXOs Fv1vFrJanHu1ktFi0v0JLBavXxha9D9+zWxxtukNu8Wmx9dYLS7vmsNm8bn3CKPFjPP7mCzW bbzFbnH7Mq/FyyM/GC2WXr/IZHG7cQWbxYTpa1kszpy+xGrRuvcIu8XhN+2sFm2rP7BarNr1 h9FB3GPNvDWMHi3NPWwel/t6mTxu3an32DnrLrvHyuVf2Dw2repk89i8pN7j3zF2jy1X21k8 +rasYvT4vEkugCeKyyYlNSezLLVI3y6BK+PUnQMsBV+kK1Z3TGZqYLwp1sXIySEhYCLR0vCG CcIWk7hwbz1bFyMXh5DAUkaJhqOXWSGcZ4wSbaf/gVUJCxRKfDx2gwkkISKwiFFi88J2Zoiq RkaJW/fvsoA4zAJrmSVetTeygrSwCRhLbF6+hA3E5hXQkli1ZAZQnIODRUBV4u0CHZCwqECE xJO5JxkhSgQlfky+xwJicwq4Sex/+AusnFlAT+L+RS2QMLOAvMTmNW+ZJzAKzELSMQuhahaS qgWMzKsYRVNLkwuKk9JzjfSKE3OLS/PS9ZLzczcxQmL46w7GpcesDjEKcDAq8fBauvGEC7Em lhVX5h5ilOBgVhLhvTEfKMSbklhZlVqUH19UmpNafIhRmoNFSZx35q73IUIC6YklqdmpqQWp RTBZJg5OqQbG1YubL3EINMtG6Nx/9Lv/87X79sXbnxa9f1Z5erbn5ErRmCbjidxOaetmOn7r lFWcbJbAM0P4FFde8JqkDUebZs+QunVqKduK0CRrhnyDBS/WnA6M685dFWmu73BaL1S8bLbI 7cDS/SnxPS/3Htq/wW/aD9YdfC3xHydHn/mz4pXfqYrZJTUxSizFGYmGWsxFxYkAzkNz4N0C AAA= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3493 Lines: 77 On 04/11/2016 05:57 AM, Chanwoo Choi wrote: > This patch updates the documentation for passive bus devices and adds the > detailed example of Exynos3250. > > Signed-off-by: Chanwoo Choi > Acked-by: MyungJoo Ham > --- > .../devicetree/bindings/devfreq/exynos-bus.txt | 250 ++++++++++++++++++++- > 1 file changed, 247 insertions(+), 3 deletions(-) > > diff --git a/Documentation/devicetree/bindings/devfreq/exynos-bus.txt b/Documentation/devicetree/bindings/devfreq/exynos-bus.txt > index 78171b918e3f..03f13d38f1a1 100644 > --- a/Documentation/devicetree/bindings/devfreq/exynos-bus.txt > +++ b/Documentation/devicetree/bindings/devfreq/exynos-bus.txt > @@ -8,22 +8,46 @@ of the bus in runtime. To monitor the usage of each bus in runtime, > the driver uses the PPMU (Platform Performance Monitoring Unit), which > is able to measure the current load of sub-blocks. > > +The Exynos SoC includes the various sub-blocks which have the each AXI bus. > +The each AXI bus has the owned source clock but, has not the only owned > +power line. The power line might be shared among one more sub-blocks. > +So, we can divide into two type of device as the role of each sub-block. > +There are two type of bus devices as following: > +- parent bus device > +- passive bus device > + > +Basically, parent and passive bus device share the same power line. > +The parent bus device can only change the voltage of shared power line > +and the rest bus devices (passive bus device) depend on the decision of > +the parent bus device. If there are three blocks which share the VDD_xxx > +power line, Only one block should be parent device and then the rest blocks > +should depend on the parent device as passive device. > + > + VDD_xxx |--- A block (parent) > + |--- B block (passive) > + |--- C block (passive) > + > There are a little different composition among Exynos SoC because each Exynos > SoC has different sub-blocks. Therefore, shch difference should be specified s/shch/such/ > in devicetree file instead of each device driver. In result, this driver > is able to support the bus frequency for all Exynos SoCs. > > -Required properties for bus device: > +Required properties for all bus devices: > - compatible: Should be "samsung,exynos-bus". > - clock-names : the name of clock used by the bus, "bus". > - clocks : phandles for clock specified in "clock-names" property. > - operating-points-v2: the OPP table including frequency/voltage information > to support DVFS (Dynamic Voltage/Frequency Scaling) feature. > + > +Required properties only for parent bus device: > - vdd-supply: the regulator to provide the buses with the voltage. > - devfreq-events: the devfreq-event device to monitor the current utilization > of buses. > > -Optional properties for bus device: > +Required properties only for passive bus device: > +- devfreq: the parent bus device. > + > +Optional properties only for parent bus device: > - exynos,saturation-ratio: the percentage value which is used to calibrate > the performance count against total cycle count. > - exynos,voltage-tolerance: the percentage value for bus voltage tolerance > @@ -34,7 +58,20 @@ Example1: > power line (regulator). The MIF (Memory Interface) AXI bus is used to > transfer data between DRAM and CPU and uses the VDD_MIF regualtor. s/regualtor/regulator/ Acked-by: Krzysztof Kozlowski Best regards, Krzysztof