From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rob Herring Subject: Re: [PATCH v7 07/13] dt-bindings: memory-controllers: add Exynos5422 DMC device description Date: Wed, 8 May 2019 15:35:15 -0500 Message-ID: References: <1557155521-30949-1-git-send-email-l.luba@partner.samsung.com> <1557155521-30949-8-git-send-email-l.luba@partner.samsung.com> <20190507170422.GA25179@bogus> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Lukasz Luba Cc: Krzysztof Kozlowski , devicetree@vger.kernel.org, "linux-kernel@vger.kernel.org" , "open list:THERMAL" , "linux-samsung-soc@vger.kernel.org" , =?UTF-8?B?QmFydMWCb21pZWogxbtvxYJuaWVya2lld2ljeg==?= , Kukjin Kim , Chanwoo Choi , Kyungmin Park , Marek Szyprowski , Sylwester Nawrocki , MyungJoo Ham , Kees Cook , Tony Lindgren , Joerg Roedel , Thierry Reding , Dmitry Osipenko , willy.mh.wolff.ml List-Id: devicetree@vger.kernel.org On Wed, May 8, 2019 at 4:45 AM Lukasz Luba wrote: > > > On 5/8/19 9:19 AM, Krzysztof Kozlowski wrote: > > On Tue, 7 May 2019 at 19:04, Rob Herring wrote: > >>> +- devfreq-events : phandles of the PPMU events used by the controller. > >>> +- samsung,syscon-chipid : phandle of the ChipID used by the controller. > >>> +- samsung,syscon-clk : phandle of the clock register set used by the controller. > >> > >> Looks like a hack. Can't you get this from the clocks property? What is > >> this for? > > > > Hi Rob, > > > > Lukasz uses these two syscon regmaps to read certain registers. For > > chipid he reads it to check the size of attached memory (only 2 GB > > version is supported). This indeed looks like a hack. However the > > second regmap (clk) is needed to get the timing data from registers > > from DMC clock driver address space. These are registers with memory > > timing so their data is not exposed anyway in common clk framework. Okay, please just explain what your accessing. Consider adding the offset as a cell in case stuff moves around on another chip. > > > > Best regards, > > Krzysztof > > Thank you Krzysztof for a fast response. I have also responded to Rob. > I wouldn't call accessing chipid registers as a hack, though. The DMC > registers do not contain information about the memory chip since it is > in phase of production the board not the chip. Thus, chipid regs (which > loads from e-fuses) are best place to put information about memory > type/size. For efuses, we have a binding (nvmem). Maybe you should use it. Rob