From mboxrd@z Thu Jan 1 00:00:00 1970 From: Richard Zhao Subject: Re: [PATCH V6 4/7] cpufreq: add clk-reg cpufreq driver Date: Thu, 12 Jan 2012 16:23:01 +0800 Message-ID: <20120112082300.GF2414@b20223-02.ap.freescale.net> References: <1325213769-11752-1-git-send-email-richard.zhao@linaro.org> <1325213769-11752-5-git-send-email-richard.zhao@linaro.org> <87aa5t25ad.fsf@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Return-path: Content-Disposition: inline In-Reply-To: <87aa5t25ad.fsf@ti.com> Sender: cpufreq-owner@vger.kernel.org To: Kevin Hilman Cc: Richard Zhao , linux@arm.linux.org.uk, arnd@arndb.de, patches@linaro.org, marc.zyngier@arm.com, catalin.marinas@arm.com, devicetree-discuss@lists.ozlabs.org, cpufreq@vger.kernel.org, rdunlap@xenotime.net, eric.miao@linaro.org, rob.herring@calxeda.com, kernel@pengutronix.de, davej@redhat.com, jamie@jamieiles.com, linaro-dev@lists.linaro.org, linux-arm-kernel@lists.infradead.org List-Id: devicetree@vger.kernel.org On Wed, Jan 11, 2012 at 03:22:34PM -0800, Kevin Hilman wrote: > Richard Zhao writes: > > > The driver get cpu operation point table from device tree cpu0 node, > > Since we already have an existing OPP infrastructure in the kernel, > seems like this driver should get OPPs by asking the OPP layer. When I created the patch, there's only omap cpufreq driver using OPP. If it depends on OPP, it might prevent users who have not adopted OPP from using the driver. > > This approach assumes the OPP layer is static at boot time and not > changing, however that's not the case in practice. > > The OPP layer could be extended to read boot-time OPPs from DT if > desired, but since the OPPs are also populated/enabled/disabled > dynamicaly on some platforms (e.g. OMAP), I think the any generic > CPUfreq driver should use the OPP interface and not DT directly. > > > and adjusts operating points using clk and regulator APIs. > > For a generic driver, the regulator used should also be configurable. > > For example, this driver currently assumes a regulator named "cpu" for > all instances. If you had separate clusters with independent voltage > control, you'd likely have a separate regulator for each cluster. The driver, for now, assumes all cpu cores uses the same clk and voltage. It's correct for most arm multi-core SoC. Do you have real case to need different voltage/clk? And the regulator will be specified in dts after cpu convert from sys device to normal device. Thanks Richard > > Kevin > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >