From: <Claudiu.Beznea@microchip.com> To: <daniel.lezcano@linaro.org>, <robh+dt@kernel.org>, <mark.rutland@arm.com>, <linux@armlinux.org.uk>, <nsekhar@ti.com>, <bgolaszewski@baylibre.com>, <monstr@monstr.eu>, <john@phrozen.org>, <ralf@linux-mips.org>, <paul.burton@mips.com>, <jhogan@kernel.org>, <lftan@altera.com>, <tglx@linutronix.de>, <vgupta@synopsys.com>, <marc.zyngier@arm.com>, <patrice.chotard@st.com>, <mcoquelin.stm32@gmail.com>, <alexandre.torgue@st.com>, <eric@anholt.net>, <wahrenst@gmx.net>, <f.fainelli@gmail.com>, <rjui@broadcom.com>, <sbranden@broadcom.com>, <bcm-kernel-feedback-list@broadcom.com>, <linus.walleij@linaro.org>, <shc_work@mail.ru>, <kgene@kernel.org>, <krzk@kernel.org>, <ysato@users.sourceforge.jp>, <liviu.dudau@arm.com>, <sudeep.holla@arm.com>, <lorenzo.pieralisi@arm.com>, <shawnguo@kernel.org>, <s.hauer@pengutronix.de>, <kernel@pengutronix.de>, <festevam@gmail.com>, <linux-imx@nxp.com>, <baohua@kernel.org>, <Nicolas.Ferre@microchip.com>, <alexandre.belloni@bootlin.com>, <Ludovic.Desroches@microchip.com>, <baruch@tkos.co.il>, <u.kleine-koenig@pengutronix.de>, <guoren@kernel.org>, <kaloz@openwrt.org>, <khalasa@piap.pl>, <ssantosh@kernel.org>, <vz@mleia.com>, <slemieux.tyco@gmail.com>, <khilman@baylibre.com>, <avifishman70@gmail.com>, <tmaimon77@gmail.com>, <tali.perry1@gmail.com>, <venture@google.com>, <yuenn@google.com>, <benjaminfair@google.com>, <afaerber@suse.de>, <manivannan.sadhasivam@linaro.org>, <narmstrong@baylibre.com>, <agross@kernel.org>, <palmer@sifive.com>, <aou@eecs.berkeley.edu>, <heiko@sntech.de>, <orsonzhai@gmail.com>, <baolin.wang@linaro.org>, <zhang.lyra@gmail.com>, <maxime.ripard@bootlin.com>, <wens@csie.org>, <thierry.reding@gmail.com>, <jonathanh@nvidia.com>, <linux@prisktech.co.nz>, <john.stultz@linaro.org>, <sboyd@kernel.org>, <matthias.bgg@gmail.com> Cc: <devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>, <linux-arm-kernel@lists.infradead.org>, <linux-mips@vger.kernel.org>, <nios2-dev@lists.rocketboards.org>, <linux-snps-arc@lists.infradead.org>, <linux-stm32@st-md-mailman.stormreply.com>, <linux-rpi-kernel@lists.infradead.org>, <linux-samsung-soc@vger.kernel.org>, <uclinux-h8-devel@lists.sourceforge.jp>, <linux-amlogic@lists.infradead.org>, <openbmc@lists.ozlabs.org>, <linux-oxnas@groups.io>, <linux-arm-msm@vger.kernel.org>, <linux-unisoc@lists.infradead.org>, <linux-riscv@lists.infradead.org>, <linux-rockchip@lists.infradead.org>, <linux-tegra@vger.kernel.org>, <linux-mediatek@lists.infradead.org> Subject: Re: [PATCH 0/7] add support for clocksource/clockevent DT selection Date: Mon, 21 Oct 2019 08:58:10 +0000 Message-ID: <215a1cd3-b1a8-5171-d70c-8d8081038e7f@microchip.com> (raw) In-Reply-To: <8e9f709f-2ded-c666-26e0-9235d6107c34@linaro.org> Hi Daniel, On 18.10.2019 23:24, Daniel Lezcano wrote: > Hi Claudiu, > > On 15/10/2019 11:23, Claudiu.Beznea@microchip.com wrote: > > [ ... ] > >> The timer clock source could be divided by MR.PRES + 1. >> >> So, I used the clock-frequency DT binding to let user choose the timer's >> frequency. Based on the value provided via this DT binding the best clock >> source and prescaler is chosen via mchp_pit64b_pres_prepare() function. > > I'm willing to take the driver but I doubt the purpose of the > clock-frequency is to let the user choose the frequency. > I found this approach in the following already integrated drivers: drivers/clocksource/armv7m_systick.c drivers/clocksource/bcm2835_timer.c drivers/clocksource/bcm_kona_timer.c drivers/clocksource/mips-gic-timer.c drivers/clocksource/mps2-timer.c drivers/clocksource/timer-qcom.c drivers/clocksource/arm_arch_timer.c Looking through the documentation of these, most of them document this DT property as the frequency of the clock that drivers the timer, but none of them seems to have some IP internal dividers so that the timer to tick at different frequency than the clock that feeds the IP. From the documentation of the above drivers; drivers/clocksource/armv7m_systick.c - clock-frequency : The rate in HZ in input of the ARM SysTick drivers/clocksource/bcm2835_timer.c - clock-frequency : The frequency of the clock that drives the counter, in Hz. drivers/clocksource/bcm_kona_timer.c - clock-frequency: frequency that the clock operates drivers/clocksource/mips-gic-timer.c clock-frequency : Clock frequency at which the GIC timers operate. drivers/clocksource/mps2-timer.c - clock-frequency : The rate in HZ in input of the ARM MPS2 timer drivers/clocksource/timer-qcom.c - clock-frequency : The frequency of the debug timer and the general purpose timer(s) in Hz in that order. This is why I also chose this DT bindings. If you want I can stick to a fixed frequency hard coded in the driver. Please let me know if this would be OK for you. Thank you, Claudiu Beznea > > [ ... ] > >
next prev parent reply index Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-09-10 13:47 Claudiu Beznea 2019-09-10 13:47 ` [PATCH 1/7] clocksource/drivers/c-sky: request timer_of_init only for probing CPU Claudiu Beznea 2019-09-10 13:47 ` [PATCH 2/7] clocksource: change timer registration macros Claudiu Beznea 2019-09-10 13:47 ` [PATCH 3/7] clocksource/timer_of: use BIT() macro Claudiu Beznea 2019-09-10 13:47 ` [PATCH 4/7] dt-bindings: chosen: Add clocksource and clockevent selection Claudiu Beznea 2019-09-11 7:34 ` Neil Armstrong 2019-09-10 13:47 ` [PATCH 5/7] clocksource/drivers/timer-of: add support support for timer's functionalities Claudiu Beznea 2019-09-10 13:47 ` [PATCH 6/7] drivers/clocksource/timer-of: keep declaration on one line Claudiu Beznea 2019-09-10 13:47 ` [PATCH 7/7] clocksource/drivers/integrator-ap: parse the chosen node Claudiu Beznea 2019-09-25 17:19 ` [PATCH 0/7] add support for clocksource/clockevent DT selection Daniel Lezcano 2019-09-26 8:42 ` Claudiu.Beznea 2019-10-02 13:35 ` Claudiu.Beznea 2019-10-03 10:43 ` Claudiu.Beznea 2019-10-13 18:16 ` Daniel Lezcano 2019-10-15 9:23 ` Claudiu.Beznea 2019-10-18 20:24 ` Daniel Lezcano 2019-10-21 8:58 ` Claudiu.Beznea [this message] 2019-10-21 14:17 ` Daniel Lezcano
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