From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tero Kristo Subject: Re: [4.4-rc][PATCH] ARM: dts: am4372: fix clock source for arm twd and global timers Date: Mon, 30 Nov 2015 10:25:56 +0200 Message-ID: <565C0814.3000001@ti.com> References: <1448653468-24908-1-git-send-email-grygorii.strashko@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1448653468-24908-1-git-send-email-grygorii.strashko-l0cyMroinI0@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Grygorii Strashko , tony-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org Cc: nsekhar-l0cyMroinI0@public.gmane.org, linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Felipe Balbi List-Id: devicetree@vger.kernel.org On 11/27/2015 09:44 PM, Grygorii Strashko wrote: > ARM TWD and Global timer are clocked by PERIPHCLK which is MPU_CLK/2. > But now they are clocked by dpll_mpu_m2_ck == MPU_CLK and, as result. > Timekeeping core misbehaves. For example, execution of command > "sleep 5" will take 10 sec instead of 5. > > Hence, fix it by adding mpu_periphclk ("fixed-factor-clock") and use > it for clocking ARM TWD and Global timer (same way as on OMAP4). > > Cc: Tony Lindgren > Cc: Felipe Balbi > Cc: Tero Kristo > Fixes:commit 8cbd4c2f6a99 ("arm: boot: dts: am4372: add ARM timers and SCU nodes") > Signed-off-by: Grygorii Strashko > --- > arch/arm/boot/dts/am4372.dtsi | 4 ++-- > arch/arm/boot/dts/am43xx-clocks.dtsi | 8 ++++++++ > 2 files changed, 10 insertions(+), 2 deletions(-) > > diff --git a/arch/arm/boot/dts/am4372.dtsi b/arch/arm/boot/dts/am4372.dtsi > index d83ff9c..de8791a 100644 > --- a/arch/arm/boot/dts/am4372.dtsi > +++ b/arch/arm/boot/dts/am4372.dtsi > @@ -74,7 +74,7 @@ > reg = <0x48240200 0x100>; > interrupts = ; > interrupt-parent = <&gic>; > - clocks = <&dpll_mpu_m2_ck>; > + clocks = <&mpu_periphclk>; > }; > > local_timer: timer@48240600 { > @@ -82,7 +82,7 @@ > reg = <0x48240600 0x100>; > interrupts = ; > interrupt-parent = <&gic>; > - clocks = <&dpll_mpu_m2_ck>; > + clocks = <&mpu_periphclk>; > }; > > l2-cache-controller@48242000 { > diff --git a/arch/arm/boot/dts/am43xx-clocks.dtsi b/arch/arm/boot/dts/am43xx-clocks.dtsi > index cc88728..2ff58b1 100644 > --- a/arch/arm/boot/dts/am43xx-clocks.dtsi > +++ b/arch/arm/boot/dts/am43xx-clocks.dtsi > @@ -259,6 +259,14 @@ > ti,invert-autoidle-bit; > }; > > + mpu_periphclk: mpu_periphclk { > + #clock-cells = <0>; > + compatible = "fixed-factor-clock"; > + clocks = <&dpll_mpu_ck>; I don't think this is correct, ARM core is fed dpll_mpu_m2_ck, where the divisor value can potentially differ from 1. If you feed this clock directly from dpll_mpu_ck, you bypass this divisor. Did you check what is the impact of cpufreq on the ARM TWD/timers? -Tero > + clock-mult = <1>; > + clock-div = <2>; > + }; > + > dpll_ddr_ck: dpll_ddr_ck { > #clock-cells = <0>; > compatible = "ti,am3-dpll-clock"; > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html